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  • Li-diffusion at the interface between Li-metal and [Pyr14][TFSI]-ionic liquid:Ab initiomolecular dynamics simulations
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Boris V. Merinov, Saber Naserifar, Sergey V. Zybin, Sergey Morozov, William A. GoddardIII, Jinuk Lee, Jae Hyun Lee, Hyea Eun Han, Young Cheol Choi, Seung Ha Kim

    We previously reported comprehensive density functional theory-molecular dynamics (DFT-MD) at 400 K to determine the composition and structure of the solid electrolyte interface (SEI) between a Li anode and [Pyr14][TFSI] ionic liquid. In this paper, we examined diffusion rates in both the Li-electrode region and SEI compact layer in smaller 83Li/2[TFSI] and larger 164Li/4[TFSI] systems. At 400 K, the Li-diffusion constant in the Li-region is 1.35 × 10−10 m2/s for 83Li/2[TFSI] and 5.64 × 10−10 m2/s for 164Li/4[TFSI], while for the SEI it is 0.33 × 10−10 m2/s and 0.22 × 10−10 m2/s, thus about one order slower in the SEI compared to the Li-region. This Li-diffusion is dominated by hopping from the neighbor shell of one F or O to the neighbor shell of another. Comparing the Li-diffusion at different temperatures, we find that the activation energy is 0.03 and 0.11 eV for the Li-region in the smaller and larger systems, respectively, while for the SEI it is 0.09 and 0.06 eV.

    更新日期:2020-01-22
  • The multi-configurational time-dependent Hartree approach in optimized second quantization: Imaginary time propagation and particle number conservation
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Thomas Weike, Uwe Manthe

    The multilayer multiconfigurational time-dependent Hartree (MCTDH) in optimized second quantization representation (oSQR) approach combines the tensor contraction scheme of the multilayer MCTDH approach with the use of an optimized time-dependent orbital basis. Extending the original work on the subject [U. Manthe and T. Weike, J. Chem. Phys. 146, 064117 (2017)], here MCTDH-oSQR propagation in imaginary time and properties related to particle number conservation are studied. Differences between the orbital equation of motion in real and imaginary time are highlighted and a new gauge operator, which facilitates efficient imaginary time propagation, is introduced. Studying Bose-Hubbard models, particle number conservation in MCTDH-oSQR calculations is investigated in detail. Interesting properties of the single-particle functions used in the multilayer MCTDH representation are identified. Based on these results, a tensor contraction scheme, which explicitly utilizes particle number conservation, is suggested.

    更新日期:2020-01-22
  • System–bath entanglement theorem with Gaussian environments
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Peng-Li Du, Yao Wang, Rui-Xue Xu, Hou-Dao Zhang, YiJing Yan

    In this work, we establish a so-called “system–bath entanglement theorem,” for arbitrary systems coupled with Gaussian environments. This theorem connects the entangled system–bath response functions in the total composite space to those of local systems, as long as the interacting bath spectral densities are given. We validate the theorem with direct evaluation via the exact dissipaton-equation-of-motion approach. Therefore, this work enables various quantum dissipation theories, which originally describe only the reduced system dynamics, for their evaluations on the system–bath entanglement properties. Numerical demonstrations are carried out on the Fano interference spectroscopies of spin–boson systems.

    更新日期:2020-01-22
  • Magnetic field effect on recombination of radicals diffusing on a two-dimensional plane
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Nikita N. Lukzen, Konstantin L. Ivanov, Vladimir M. Sadovsky, Renad Z. Sagdeev

    Magnetic Field Effects (MFEs) on the recombination of radicals, which diffuse on an infinite plane, are studied theoretically. The case of spin-selective diffusion-controlled recombination of Radical Pairs (RPs) starting from a random spin state is considered assuming uniform initial distribution of the radicals. In this situation, reaction kinetics is described by a time-dependent rate coefficient K(t), which tends to zero at long times. Strong MFEs on K(t) are predicted that originate from the Δg and hyperfine driven singlet-triplet mixing in the RP. The effects of spin relaxation on the magnetic field are studied, as well as the influence of the dipole-dipole interaction between the electron spins of the RP. In the two-dimensional case, this interaction is not averaged out by diffusion and it strongly affects the MFE. The results of this work are of importance for interpreting MFEs on lipid peroxidation, a magnetosensitive process occurring on two-dimensional surfaces of cell membranes.

    更新日期:2020-01-22
  • Hierarchical algorithm for the reaction-diffusion master equation
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Stefan Hellander, Andreas Hellander

    We have developed an algorithm coupling mesoscopic simulations on different levels in a hierarchy of Cartesian meshes. Based on the multiscale nature of the chemical reactions, some molecules in the system will live on a fine-grained mesh, while others live on a coarse-grained mesh. By allowing molecules to transfer from the fine levels to the coarse levels when appropriate, we show that we can save up to three orders of magnitude of computational time compared to microscopic simulations or highly resolved mesoscopic simulations, without losing significant accuracy. We demonstrate this in several numerical examples with systems that cannot be accurately simulated with a coarse-grained mesoscopic model.

    更新日期:2020-01-22
  • Extension of frozen natural orbital approximation to open-shell references: Theory, implementation, and application to single-molecule magnets
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Pavel Pokhilko, Daniil Izmodenov, Anna I. Krylov

    Natural orbitals are often used to achieve a more compact representation of correlated wave-functions. Using natural orbitals computed as eigenstates of the virtual–virtual block of the state density matrix instead of the canonical Hartree–Fock orbitals results in smaller errors when the same fraction of virtual space is frozen. This strategy, termed frozen natural orbital (FNO) approach, is effective in reducing the cost of regular coupled-cluster (CC) calculations and some multistate methods, such as EOM-IP-CC (equation-of-motion CC for ionization potentials). This contribution extends the FNO approach to the EOM-SF-CC ansatz (EOM-CC with spin-flip). In contrast to EOM-IP-CCSD, EOM-SF-CCSD relies on high-spin open-shell references. Using FNOs computed for an open-shell reference leads to an erratic behavior of the EOM-SF-CC energies and properties due to an inconsistent truncation of the α and β orbital spaces. A general solution to problems arising in the EOM-CC calculations utilizing open-shell references, termed OSFNO (open-shell FNO), is proposed. By means of singular value decomposition (SVD) of the overlap matrix of the α and β orbitals, the OSFNO algorithm identifies the corresponding orbitals and determines virtual orbitals corresponding to the singly occupied space. This is followed by SVD of the singlet part of the state density matrix in the remaining virtual orbital subspace. The so-computed FNOs preserve the spin purity of the open-shell orbital subspace to the extent allowed by the original reference, thus facilitating a safe truncation of the virtual space. The performance of OSFNO is benchmarked for selected diradicals and triradicals.

    更新日期:2020-01-22
  • Instanton formulation of Fermi’s golden rule in the Marcus inverted regime
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Eric R. Heller, Jeremy O. Richardson

    Fermi’s golden rule defines the transition rate between weakly coupled states and can thus be used to describe a multitude of molecular processes including electron-transfer reactions and light-matter interaction. However, it can only be calculated if the wave functions of all internal states are known, which is typically not the case in molecular systems. Marcus theory provides a closed-form expression for the rate constant, which is a classical limit of the golden rule, and indicates the existence of a normal regime and an inverted regime. Semiclassical instanton theory presents a more accurate approximation to the golden-rule rate including nuclear quantum effects such as tunneling, which has so far been applicable to complex anharmonic systems in the normal regime only. In this paper, we extend the instanton method to the inverted regime and study the properties of the periodic orbit, which describes the tunneling mechanism via two imaginary-time trajectories, one of which now travels in negative imaginary time. It is known that tunneling is particularly prevalent in the inverted regime, even at room temperature, and thus, this method is expected to be useful in studying a wide range of molecular transitions occurring in this regime.

    更新日期:2020-01-22
  • A kinetic Monte Carlo-blueprint for oxygen reduction on oxide-supported PtNi nanoalloys
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    D. Schmidt, GG. Asara, F. Baletto

    To elucidate the effect of the architecture of supported bimetallic nanocatalysts, we developed a new lattice kinetic Monte Carlo based on the classifying and counting adsorption sites with respect to their generalized coordination number. We employed this tool to estimate the activity of MgO-supported PtNi nanoalloys for oxygen reduction. We demonstrated that the presence of Ni atoms in contact with the substrate massively enhances their activity with at least a 7-order of magnitude increase in the turnover of water production with respect to the case where only Pt lay at the interface. We further discussed how the nanoalloy shape affects the activity showing that truncated octahedra are 102 more active than cuboctahedra of similar size. We explained our results in terms of their distinct distribution and occurrence of the most active sites for oxygen reduction leading to the stabilization of different chemical species during the reaction dynamics. Our results suggest that engineering multifaceted and long edge PtNi-nanoalloys with a certain chemical ordering at the support interface would improve their catalytic performance for the oxygen reduction reaction.

    更新日期:2020-01-22
  • Cumulant expansion for the treatment of light–matter interactions in arbitrary material structures
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    M. Sánchez-Barquilla, R. E. F. Silva, J. Feist

    Strong coupling of quantum emitters with confined electromagnetic modes of nanophotonic structures may be used to change optical, chemical, and transport properties of materials, with significant theoretical effort invested toward a better understanding of this phenomenon. However, a full theoretical description of both matter and light is an extremely challenging task. Typical theoretical approaches simplify the description of the photonic environment by describing it as a single mode or few modes. While this approximation is accurate in some cases, it breaks down strongly in complex environments, such as within plasmonic nanocavities, and the electromagnetic environment must be fully taken into account. This requires the quantum description of a continuum of bosonic modes, a problem that is computationally hard. We here investigate a compromise where the quantum character of light is taken into account at modest computational cost. To do so, we focus on a quantum emitter that interacts with an arbitrary photonic spectral density and employ the cumulant, or cluster, expansion method to the Heisenberg equations of motion up to first, second, and third order. We benchmark the method by comparing it with exact solutions for specific situations and show that it can accurately represent dynamics for many parameter ranges.

    更新日期:2020-01-22
  • Optimalin situelectromechanical sensing of molecular species
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-21
    Maicol A. Ochoa, Michael Zwolak

    We investigate protocols for optimal molecular detection with electromechanical nanoscale sensors under ambient conditions. Our models are representative of suspended graphene nanoribbons, which due to their piezoelectric and electronic properties provide responsive and versatile sensors. In particular, we analytically account for the corrections in the electronic transmission function and signal-to-noise ratio originating in environmental perturbations, such as thermal fluctuations and solvation effects. We also investigate the role of the sampling time in the current statistics. As a result, we formulate a protocol for optimal sensing based on the modulation of the Fermi level at a fixed bias and provide approximate forms for the current, linear susceptibility, and current fluctuations. We show how the algebraic tails in the thermally broadened transmission function affect the behavior of the signal-to-noise ratio and optimal sensing. These results provide further insights into the operation of graphene deflectometers and other techniques for electromechanical sensing.

    更新日期:2020-01-22
  • Comprehensive investigation of the triplet state electronic structure of free-base 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin by a combined advanced EPR and theoretical approach
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Antonio Barbon, Maria Giulia Dal Farra, Susanna Ciuti, Marco Albertini, Luca Bolzonello, Laura Orian, Marilena Di Valentin

    The nature of the photoexcited triplet state of free-base 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2TPPS4−) has been investigated by advanced Electron Paramagnetic Resonance (EPR) techniques combined with quantum chemical calculations. The zero-field splitting (ZFS) parameters, D and E, the orientation of the transition dipole moment in the ZFS tensor frame, and the proton hyperfine couplings have been determined by magnetophotoselection-EPR and pulse electron-nuclear double resonance spectroscopy. Both time-resolved and pulse experiments exploit the electron spin polarization of the photoexcited triplet state. Comparison of the magnetic observables with computational results, including CASSCF calculations of the ZFS interaction tensor, provides an accurate picture of the triplet-state electronic structure. The theoretical investigation has been integrated with a systematic analysis on the parent free-base porphyrin molecule to assess the effect of the sulfonatophenyl substituents on the magnetic tensors. Additionally, the magnetophotoselection effects are discussed in terms of tautomerization in the excited singlet state of H2TPPS4−.

    更新日期:2020-01-22
  • Optically-generated Overhauser dynamic nuclear polarization: A numerical analysis
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-21
    Daniel J. Cheney, Christopher J. Wedge

    Recently, an alternative approach to dynamic nuclear polarization (DNP) in the liquid state was introduced using optical illumination instead of microwave pumping. By exciting a suitable dye to the triplet state which undergoes a diffusive encounter with a persistent radical forming a quartet-doublet pair in the encounter complex, dynamic electron polarization (DEP) is generated via the radical-triplet pair mechanism. Subsequent cross-relaxation generates nuclear polarization without the need for microwave saturation of the electronic transitions. Here, we present a theoretical justification for the initial experimental results by means of numerical simulations. These allow investigation of the effects of various experimental parameters, such as radical and dye concentrations, sample geometry, and laser power, on the DNP enhancement factors, providing targets for experimental optimization. It is predicted that reducing the sample volume will result in larger enhancements by permitting a higher concentration of triplets in a sample of increased optical density. We also explore the effects of the pulsed laser rather than continuous-wave illumination, rationalizing the failure to observe the optical DNP effect under illumination conditions common to DEP experiments. Examining the influence of the illumination duty cycle, the conditions necessary to permit the use of pulsed illumination without compromising signal enhancement are determined, which may reduce undesirable laser heating effects. This first simulation of the optical DNP method therefore underpins the further development of the technology.

    更新日期:2020-01-22
  • A dominant factor of the cycloreversion reactivity of diarylethene derivatives as revealed by femtosecond time-resolved absorption spectroscopy
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Hikaru Sotome, Kanako Une, Tatsuhiro Nagasaka, Seiya Kobatake, Masahiro Irie, Hiroshi Miyasaka

    Dynamics of the cycloreversion reaction of a photochromic diarylethene derivative with a small ring-opening reaction yield (∼1%) was investigated by using femtosecond transient absorption spectroscopy. The reaction rate constant and activation barrier on the reaction coordinate were quantitatively analyzed on the basis of the temperature and excitation wavelength dependencies of the reaction yield and excited state dynamics. From the comparison of the present results with those in a more reactive derivative, we concluded that a key factor regulating the overall reaction yield is the branching ratio at the conical intersection where the excited state population is split into the product and the initial reactant. The excitation wavelength dependence of the dynamics indicated that the geometrical relaxation and vibrational cooling proceed in a few picosecond time scale behind the cycloreversion process, and the vibrational excess energy assists the molecule to climb up the energy barrier.

    更新日期:2020-01-22
  • Measurement of electron affinity of iridium atom and photoelectron angular distributions of iridium anion
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Yuzhu Lu, Jing Zhao, Rulin Tang, Xiaoxi Fu, Chuangang Ning

    The latest electron affinity value of an iridium atom is 1.564 36(15) eV, determined via a method based on the Wigner threshold law by Bilodeau and co-workers. However, they observed a significant deviation from the Wigner threshold law in the threshold photodetachment experiment. To address this dilemma, we conducted high-resolution photoelectron spectroscopy of Ir− via the slow-electron velocity-map imaging method in combination with an ion trap. The electron affinity of Ir was measured to be 12 614.97(9) cm−1 or 1.564 057(11) eV. We find that the Wigner threshold law is still valid for the threshold photodetachment of Ir− through a p-wave fitting of the photodetachment channel Ir−5d86s23F4→Ir5d86sb4F9/2. The photoelectron angular distributions of photodetachment channels Ir−5d86s23F4→Ir5d76s2a4F9/2 and Ir−5d86s23F4→Ir5d86sb4F9/2 were also investigated. The behavior of anisotropy parameter β indicates a strong interaction between the two channels. Moreover, the energy level 3P2 of Ir−, which was not observed in the previous works, was experimentally determined to be 4163.24(16) cm−1 above the ground state.

    更新日期:2020-01-22
  • Exploring the sterically disfavored binding of acetylene to a geminal olefinic hydrogen-fluorine atom pair: The microwave spectrum and molecular structure ofcis-1,2-difluoroethylene–acetylene
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Helen O. Leung, Mark D. Marshall

    The microwave rotational spectrum of the gas-phase bimolecular heterodimer formed between cis-1,2-difluoroethylene and acetylene is obtained using Fourier transform microwave spectroscopy from 5.9 to 21.2 GHz. Rotational constants derived from the analysis of the spectra for the normal isotopologue and singly substituted 13C isotopologues, obtained in natural abundance, allow the determination of the structure of the complex, which, in the absence of a fluorine-hydrogen atom pair located cis to each other, adopts a sterically disfavored geometry (“side-binding”) in which the acetylene interacts with a geminal fluorine-hydrogen atom pair. Structural details are found to be similar to those of previously studied heterodimers with side-binding of acetylene to fluorine while reflecting the degree of halosubstitution. A detailed comparison with the (Z)-1-chloro-2-fluoroethylene-acetylene complex reveals information regarding the relaxed steric requirements for hydrogen bonding to chlorine as opposed to hydrogen bonding to fluorine.

    更新日期:2020-01-22
  • An investigation of the anomalous asymptotic behavior of elastic electron scattering of helium
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Ya-Wei Liu, Tao Xiong, Xin-Chao Huang, Ke Yang, Kuan-Li Yu, Nozomu Hiraoka, Ku-Ding Tsuei, Lin-Fan Zhu

    For the inelastic electron scattering of atoms and molecules, a consensus has been reached that the first Born approximation is easily approached by decreasing the momentum transfer at the same impact electron energy or increasing the impact electron energy at the same momentum transfer. Although this consensus is applicable for the elastic electron scattering of most atoms and molecules, it is violated for helium where the experimental differential cross sections deviate from the first Born approximation prediction gradually with the decrease of squared momentum transfer at the same impact electron energy. Since this anomalous phenomenon was observed more than 40 years ago, the intrinsic mechanism is not explicit. In the present work, using the high-resolution x-ray scattering, we isolate the scattering contribution from the nucleus and directly obtain the pure electronic structure of helium. Then, the anomalous asymptotic behavior of the elastic electron scattering of helium has been elucidated, i.e., in the small squared momentum transfer region, the scattering contribution from the target’s electrons is counteracted by the one from the atomic nucleus, which results in the residual contribution beyond the first Born approximation being drastically enlarged.

    更新日期:2020-01-22
  • Effects of cavitation on Kármán vortex behind circular-cylinder arrays: A molecular dynamics study
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Yuta Asano, Hiroshi Watanabe, Hiroshi Noguchi

    The effects of cavitation on the flow around a circular-cylinder array are studied by using a molecular dynamics simulation. Cavitation significantly affects vortex shedding characteristics. As the cavitation develops, the vibration acting on the cylinders decreases and eventually disappears. The further cavitation development generates a longer vapor region next to the cylinders, and the vortex streets are formed at further positions from the cylinders. The neighboring Kármán vortexes are synchronized in the antiphase in the absence of the cavitation. This synchronization is weakened by the cavitation, and an asymmetric wake mode can be induced. These findings help mechanical designs of fluid machinery that include cylinder arrays.

    更新日期:2020-01-22
  • A collective elastic fluctuation mechanism for decoupling and stretched relaxation in glassy colloidal and molecular liquids
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Shi-Jie Xie, Kenneth S. Schweizer

    We propose a microscopic theory for the decoupling of self-diffusion and structural relaxation in glass-forming liquids within the Elastically Collective Nonlinear Langevin Equation (ECNLE) activated dynamics framework. Our central hypothesis is that the heterogeneity relevant to this problem is static fluctuations of local density on the scale of 3–4 particle diameters and how this changes local packing correlations. These fluctuations modify the degree of dynamical cage expansion that mechanistically couples intracage large amplitude hopping and longer range collective elasticity in ECNLE theory. Decoupling only emerges in the deeply supercooled regime where the strongly temperature dependent elastic barrier becomes non-negligible relative to its noncooperative local analog. The theory makes predictions for various aspects of the decoupling phenomenon, including apparent fractional power law Stokes-Einstein behavior, that appear to be consistent with experiments and simulations on hard sphere fluids and molecular liquids. Of central importance is a microscopic connection between the barrier fluctuation variance and most probable barrier height. Sensible results are also obtained for the nonexponential stretching of a generic relaxation time correlation function and its temperature evolution. Nonuniversality can arise from the relative importance of the local and collective barriers (related to fragility) and the precise magnitude of the length scale that defines the transition from local cage to elastic physics. Comparison is made with a traplike model based on a Gaussian distribution of barriers.

    更新日期:2020-01-22
  • Reorientational dynamics of trimethoxyboroxine: A molecular glass former studied by dielectric spectroscopy and11B nuclear magnetic resonance
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-21
    Lars Hoffmann, Joachim Beerwerth, Dominik Greim, Jürgen Senker, Christian Sternemann, Wolf Hiller, Roland Böhmer

    In this work, trimethoxyboroxine (TMB) is identified as a small-molecule glass former. In its viscous liquid as well as glassy states, static and dynamic properties of TMB are explored using various techniques. It is found that, on average, the structure of the condensed TMB molecules deviates from threefold symmetry so that TMB’s electric dipole moment is nonzero, thus rendering broadband dielectric spectroscopy applicable. This method reveals the super-Arrhenius dynamics that characterizes TMB above its glass transition, which occurs at about 204 K. To extend the temperature range in which the molecular dynamics can be studied, 11B nuclear magnetic resonance experiments are additionally carried out on rotating and stationary samples: Exploiting dynamic second-order shifts, spin-relaxation times, line shape effects, as well as stimulated-echo and two-dimensional exchange spectroscopy, a coherent picture regarding the dynamics of this glass former is gained.

    更新日期:2020-01-22
  • Dependence of stability and electronic and optical properties of perovskite quantum dots on capping ligand chain length
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-15
    Evan Thomas Vickers, Ke Xu, Xueming Li, Jin Zhong Zhang

    Methylammonium lead bromide (MAPbBr3) perovskite quantum dots (PQDs) passivated with capping ligands with different chain length, including butylamine-valeric acid (BUTY-VA), octylamine-caprylic acid (OCTY-CA), and dodecylamine-lauric acid (DODE-LA), are investigated to determine an optimized capping layer thickness for maximizing both electronic and antimoisture properties of perovskite materials in optoelectronic devices. The photoluminescence quantum yield (PLQY) is observed to be chain length dependent, where the PLQY of BUTY-VA, OCTY-CA, and DODE-LA MAPbBr3 PQDs is 82% ± 4%, 68% ± 7%, and 18% ± 2%, respectively. Electrochemical impedance spectroscopy (EIS) measurements of each PQD film reveal that there is a slight increase in conductivity from reducing the capping ligand chain length from 8 carbon atoms (OCTY-CA) to 4 carbon atoms (BUTY-VA). Using the Butler-Volmer equation, the charge transfer factor β for BUTY-VA and OCTY-CA MAPbBr3 PQD films in a tetrabutylammonium hexafluorophosphate-dichloromethane electrolyte solution was calculated to be 0.36 and 0.31, respectively. From an Arrhenius analysis, the activation energy (Ea) for charge transport between the PQD film and the electrolyte was calculated to be 77 and 90 meV for BUTY-VA and OCTY-CA MAPbBr3 PQD films, respectively. Moreover, passivating PQDs with capping ligands with 12 carbon atoms (DODE-LA) almost completely insulates the PQDs and diminishes charge transport. This is also observed in transient photocurrent density measurements. The results suggest that the inter-PQD distance in this solid film is too long for effective tunneling to occur. However, using BUTY-VA capping ligands to improve electronic properties of PQD solid film comes with a cost of stability.

    更新日期:2020-01-22
  • Understanding size dependence of phase stability and band gap in CsPbI3perovskite nanocrystals
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Ruo Xi Yang, Liang Z. Tan

    Inorganic halide perovskites CsPbX3 (X = Cl, Br, I) have been widely studied as colloidal quantum dots for their excellent optoelectronic properties. Not only is the long-term stability of these materials improved via nanostructuring, their optical bandgaps are also tunable by the nanocrystal (NC) size. However, theoretical understanding of the impact of the NC size on the phase stability and bandgap is still lacking. In this work, the relative phase stability of CsPbI3 as a function of the crystal size and the chemical potential is investigated by density functional theory. The optically active phases (α- and γ-phase) are found to be thermodynamically stabilized against the yellow δ-phase by reducing the size of the NC below 5.6 nm in a CsI-rich environment. We developed a more accurate quantum confinement model to predict the change in bandgaps at the sub–10 nm regime by including a finite-well effect. These predictions have important implications for synthesizing ever more stable perovskite NCs and bandgap engineering.

    更新日期:2020-01-22
  • Control of interfacial pH in mesoporous silica nanoparticles via surface functionalization
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Dilini Singappuli-Arachchige, Igor I. Slowing

    The pH at silica-water interfaces (pHint) was measured by grafting a dual emission fluorescent probe (SNARF) onto the surface of mesoporous silica nanoparticles (MSN). The values of pHint of SNARF-MSN suspended in water were different from the pH of the bulk solution (pHbulk). The addition of acid or base to aqueous suspensions of SNARF-MSN induced much larger changes in pHbulk than pHint, indicating that the interface has buffering capacity. Grafting additional organic functional groups onto the surface of SNARF-MSN controls the pHint of its buffering region. The responses of pHint to variations in pHbulk are consistent with the acid/base properties of the surface groups as determined by their pKa and are affected by electrostatic interactions between charged interfacial species as evidenced by the dependence of ζ-potential on pHbulk. Finally, as a proof of principle, we demonstrate that the hydrolysis rate of an acid-sensitive acetal can be controlled by adjusting pHint via suitable functionalization of the MSN surface. Our findings can lead to the development of nanoreactors that protect sensitive species from adverse conditions and tune their chemical reactivity.

    更新日期:2020-01-22
  • Correlation between structural phase transition and surface chemical properties of thin film SrRuO3/SrTiO3(001)
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Dongwoo Kim, Hojoon Lim, Sung Soo Ha, Okkyun Seo, Sung Su Lee, Jinwoo Kim, Ki-jeong Kim, Lucia Perez Ramirez, Jean-Jacques Gallet, Fabrice Bournel, Ji Young Jo, Slavomir Nemsak, Do Young Noh, Bongjin Simon Mun

    The correlation between the structural phase transition (SPT) and oxygen vacancy in SrRuO3 (SRO) thin films was investigated by in situ X-ray diffraction (XRD) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS). In situ XRD shows that the SPT occurs from a monoclinic SRO phase to a tetragonal SRO phase near ∼200 °C, regardless of the pressure environment. On the other hand, significant core level shifts in both the Ru and Sr photoemission spectra are found under ultrahigh vacuum, but not under the oxygen pressure environment. The directions and behavior of the core level shift of Ru and Sr are attributed to the formation of oxygen vacancy across the SPT temperature of SRO. The analysis of in situ XRD and AP-XPS results provides an evidence for the formation of metastable surface oxide possibly due to the migration of internal oxygen atoms across the SPT temperature, indicating the close relationship between oxygen vacancy and SPT in SRO thin films.

    更新日期:2020-01-22
  • Arbitrary control of the diffusion potential between a plasmonic metal and a semiconductor by an angstrom-thick interface dipole layer
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Tomoya Oshikiri, Hiroki Sawayanagi, Keisuke Nakamura, Kosei Ueno, Takayoshi Katase, Hiromichi Ohta, Hiroaki Misawa

    Localized surface plasmon resonances (LSPRs) are gaining considerable attention due to the unique far-field and near-field optical properties and applications. Additionally, the Fermi energy, which is the chemical potential, of plasmonic nanoparticles is one of the key properties to control hot-electron and -hole transfer at the interface between plasmonic nanoparticles and a semiconductor. In this article, we tried to control the diffusion potential of the plasmonic system by manipulating the interface dipole. We fabricated solid-state photoelectric conversion devices in which gold nanoparticles (Au-NPs) are located between strontium titanate (SrTiO3) as an electron transfer material and nickel oxide (NiO) as a hole transport material. Lanthanum aluminate as an interface dipole layer was deposited on the atomic layer scale at the three-phase interface of Au-NPs, SrTiO3, and NiO, and the effect was investigated by photoelectric measurements. Importantly, the diffusion potential between the plasmonic metal and a semiconductor can be arbitrarily controlled by the averaged thickness and direction of the interface dipole layer. The insertion of an only one unit cell (uc) interface dipole layer, whose thickness was less than 0.5 nm, dramatically controlled the diffusion potential formed between the plasmonic nanoparticles and surrounding media. This is a new methodology to control the plasmonic potential without applying external stimuli, such as an applied potential or photoirradiation, and without changing the base materials. In particular, it is very beneficial for plasmonic devices in that the interface dipole has the ability not only to decrease but also to increase the open-circuit voltage on the order of several hundreds of millivolts.

    更新日期:2020-01-22
  • Time-resolved temperature-jump measurements and steady-state thermal imaging of nanoscale heat transfer of gold nanostructures on AlGaN:Er3+thin films
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    Kristina Shrestha, Juvinch R. Vicente, Ali Rafiei Miandashti, Jixin Chen, Hugh H. Richardson

    For a nanostructure sitting on top of an AlGaN:Er3+ thin film, a new thermal imaging technique is presented where dual cameras collect bandpass filtered videos from the H and S bands of Er3+ emission. We combine this thermal imaging technique with our newly developed time-resolved temperature measurement technique which relies on luminescence thermometry using Er3+ emission. This technique collects time-resolved traces from the H and S bands of Er3+ emission. The H and S signal traces are then used to reconstruct the time-resolved temperature transient when a nanostructure is illuminated with a pulsed 532 nm light. Two different types of samples are interrogated with these techniques (drop-casted gold nanosphere cluster and lithographically prepared gold nanodot) on the AlGaN:Er3+ film. Steady-state and time-resolved temperature data are collected when the samples are immersed in air and water. The results of time-resolved temperature-jump measurements from a cluster of gold nanospheres show extremely slow heat transfer when the cluster is immersed in water and nearly 200-fold increase when immersed in air. The low thermal diffusivity for the cluster in water suggests poor thermal contact between the cluster and the thermal bath. The lithographically prepared nanodot has much better adhesion to the AlGaN film, resulting in much higher thermal diffusivity in both air and water. This proof-of-concept demonstration opens a new way to measure the dynamics of the local heat generation and dissipation at the nanoparticle-media interface.

    更新日期:2020-01-22
  • Effects of fast back-fusion of charge transfer excimers on magneto-photocurrent in organic light emitting diodes
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-17
    D. Nikiforov, B. Khachatryan, N. Tessler, E. Ehrenfreund

    We report the magnetic field dependence of the magneto-photocurrent (MPC) in organic light emitting diodes made of homo-polymer organic layers and compare it to the measured magneto-conductance (MC) in the same diodes. We find that the response MPC(B) is very different from MC(B) in at least two respects. (a) The low field (B < 50 mT) response of MPC(B) is narrower by a factor of ∼5 from that of MC(B). (b) At high fields (B > 4 T), MPC(B) has a stronger dependence on B, d(MPC)/dB ∼ 5d(MC)/dB. We attribute these differences to a unique feature of charge transfer excimers that are responsible for MPC: sub-ns fast fusion back to singlet excitons and slow (ns to μs) dissociation to free charges. In contrast, MC(B) is determined by long lived (>10 ns) polaron pairs having singlet and triplet dissociation rates of the same order.

    更新日期:2020-01-22
  • Particle separation induced by triangle obstacles in a straight channel
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Jian-Chun Wu, Tian-Wen Dong, Gui-Wen Jiang, Meng An, Bao-Quan Ai

    Efficient separation of particles has ever-growing importance in both fundamental research and nanotechnological applications. However, such particles usually suffer from some fluctuations from external surroundings and outside intervention from unknown directions. Here, we numerically investigate the transport of Brownian particles in a straight channel with regular arrays of equilateral triangle obstacles. The particles can be rectified by the triangle obstacles under the action of an oscillating (square wave) force. At the given amplitude and frequency of the oscillating force, the transport is sensitively dependent on the force direction and particle size. In the cases of longitudinal and transversal oscillating force, the particles with different sizes exhibit different transport behaviors. Interestingly, under a constant force in the longitudinal direction, the phenomenon of particle separation is observed, where the particles with different radii will move in different directions. Furthermore, we also study the transport of Brownian particles driven by a tilt oscillating force. By choosing proper force directions, we can observe the gating phenomenon and transport reversal. Under different driving conditions, we can separate particles of different sizes and make them move in opposite directions.

    更新日期:2020-01-22
  • One-electron oxidation of TAT-motif triplex DNA and the ensuing Hoogsteen hydrogen-bonding dissociation
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-15
    Qian Zhou, Yinghui Wang, Xiaojuan Dai, Chunfan Yang, Jialong Jie, Hongmei Su

    One-electron oxidation of adenine (A) leads initially to the formation of adenine radical cation (A•+). Subsequent deprotonation of A•+ can provoke deoxyribonucleic acid (DNA) damage, which further causes senescence, cancer formation, and even cell death. However, compared with considerable reports on A•+ reactions in free deoxyadenosine (dA) and duplex DNA, studies in non-B-form DNA that play critical biological roles are rare at present. It is thus of vital importance to explore non-B-form DNA, among which the triplex is an emerging topic. Herein, we investigate the deprotonation behavior of A•+ in the TAT triplex with continuous A bases by time-resolved laser flash photolysis. The rate constants for the one-oxidation of triplex 8.4 × 108 M−1 s−1 and A•+ deprotonation 1.3 × 107 s−1 are obtained. The kinetic isotope effect of A•+ deprotonation in the TAT triplex is 1.8, which is characteristic of a direct release of the proton into the solvent similar to free base dA. It is thus elucidated that the A•+ proton bound with the third strand is most likely to be released into the solvent because of the weaker Hoogsteen H-bonding interaction and the presence of the highly mobile hydration waters within the third strand. Additionally, it is confirmed through Fourier transform infrared spectroscopy that the deprotonation of A•+ results in the dissociation of the third strand and disruption of the secondary structure of the triplex. These results provide valuable kinetic data and in-depth mechanistic insights for understanding the adenine oxidative DNA damage in the triplex.

    更新日期:2020-01-22
  • Automatic error control during forward flux sampling of rare events in master equation models
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Max C. Klein, Elijah Roberts

    Enhanced sampling methods, such as forward flux sampling (FFS), have great capacity for accelerating stochastic simulations of nonequilibrium biochemical systems involving rare events. However, the description of the tradeoffs between simulation efficiency and error in FFS remains incomplete. We present a novel and mathematically rigorous analysis of the errors in FFS that, for the first time, covers the contribution of every phase of the simulation. We derive a closed form expression for the optimally efficient count of samples to take in each FFS phase in terms of a fixed constraint on sampling error. We introduce a new method, forward flux pilot sampling (FFPilot), that is designed to take full advantage of our optimizing equation without prior information or assumptions about the phase weights and costs along the transition path. In simulations of both single and multidimensional gene regulatory networks, FFPilot is able to completely control sampling error. We then discuss how memory effects can introduce additional error when relaxation along the transition path is slow. This extra error can be traced to correlations between the FFS phases and can be controlled by monitoring the covariance between them. Finally, we show that, in sets of simulations with matched error, FFPilot is on the order of tens-to-hundreds of times faster than direct sampling and noticeably more efficient than previous FFS methods.

    更新日期:2020-01-22
  • Glycosidic linkage flexibility: Theψtorsion angle has a bimodal distribution inα-L-Rhap-(1→2)-α-L-Rhap-OMe as deduced from13C NMR spin relaxation
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    Mirco Zerbetto, Antonino Polimeno, Göran Widmalm

    The molecular dynamics (MD) computer simulation technique is powerful for the investigation of conformational equilibrium properties of biomolecules. In particular, free energy surfaces of the torsion angles (those degrees of freedom from which the geometry mostly depends) allow one to access conformational states, as well as kinetic information, i.e., if the transitions between conformational states occur by simple jumps between wells or if conformational regions close to these states also are populated. The information obtained from MD simulations may depend substantially on the force field employed, and thus, a validation procedure is essential. NMR relaxation data are expected to be highly sensitive to the details of the torsional free energy surface. As a case-study, we consider the disaccharide α-l-Rhap-(1 → 2)-α-l-Rhap-OMe that features only two important torsion angles, ϕ and ψ, which define the interglycosidic orientation of the sugar residues relative to each other, governed mainly by the exo-anomeric effect and steric interactions, respectively. In water, a ψ− state is preferred, whereas in DMSO, it is a ψ+ state, suggesting inherent flexibility at the torsion angle. MD simulations indicated that bistable potentials describe the conformational region well. To test whether a unimodal distribution suffices or if a bimodal distribution better represents molecular conformational preferences, we performed an alchemical morphing of the torsional free energy surface and computed T1, T2, and NOE 13C NMR relaxation data that were compared to experimental data. All three NMR observables are substantially affected by the morphing procedure, and the results strongly support a bimodal Boltzmann equilibrium density with a major and a minor conformational state bisected at ψ ≈ 0°, in accord with MD simulations in an explicit solvent.

    更新日期:2020-01-22
  • Electromagnetic field modulates aggregation propensity of amyloid peptides
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-16
    N. Todorova, A. Bentvelzen, I. Yarovsky

    Nonthermal effects of the electromagnetic (EM) field in the radio and microwave frequency ranges on basic biological matter are difficult to detect and thus remain poorly understood. In this work, all-atom nonequilibrium molecular dynamics simulations were performed to investigate the molecular mechanisms of an amyloidogenic peptide response to nonionizing radiation of varying field characteristics. The results showed that the EM field induced peptide conformations dependent on the field frequency and strength. At the high field strength (0.7 V/nmrms), the peptide explored a wider conformational space as the frequency increased from 1.0 to 5.0 GHz. At the intermediate strength fields (0.07–0.0385 V/nmrms), the frequencies of 1.0 and 2.5 GHz resulted in the peptide being trapped in specific conformations, with 1.0 GHz enabling both fibril-forming and fibril-inhibiting conformations, while 2.5 GHz led to formation of mostly fibril-forming conformations. In contrast, the 5.0 GHz frequency caused increased peptide dynamics and more extended conformations with fibril-enabling aromatic side-chain arrangement akin to the structures formed under ambient conditions. All the simulated frequencies at low strength fields (0.007–0.0007 V/nmrms) resulted in the formation of amyloid-prone hairpin conformations similar to those formed under the weak static electric field and ambient conditions. These results suggest that specific ranges of EM field parameters produce peptide conformations unfavorable for formation of amyloid fibrils, a phenomenon that can be exploited in treatment and prevention of amyloid diseases. Alternatively, EM field parameters can be selected to modulate the formation of well-ordered peptide assemblies as a rational design strategy for engineering biocompatible materials.

    更新日期:2020-01-22
  • Transient absorption microscopy: Technological innovations and applications in materials science and life science
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-09
    Yifan Zhu, Ji-Xin Cheng

    Transient absorption (TA) spectroscopy has been extensively used in the study of excited state dynamics of various materials and molecules. The transition from TA spectroscopy to TA microscopy, which enables the space-resolved measurement of TA, is opening new investigations toward a more complete picture of excited state dynamics in functional materials, as well as the mapping of crucial biopigments for precision diagnosis. Here, we review the recent instrumental advancement that is pushing the limit of spatial resolution, detection sensitivity, and imaging speed. We further highlight the emerging application in materials science and life science.

    更新日期:2020-01-14
  • Near-unity photoluminescence quantum yield in inorganic perovskite nanocrystals by metal-ion doping
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-09
    Ghada H. Ahmed, Jun Yin, Osman M. Bakr, Omar F. Mohammed

    The luminescence and charge transport properties of inorganic CsPbX3 perovskite nanocrystals (NCs) make them attractive candidates for various optoelectronic applications, such as lasing, X-ray imaging, light communication, and light-emitting diodes (LEDs). However, to realize cutting-edge device performance, high-quality NCs with high photoluminescence quantum yields (PLQYs) are essential. Therefore, substantial efforts and progress have been made to attain superior design/engineering and optimization of the inorganic NCs with a focus on surface quality, reduced nonradiative charge carrier recombination centers, and improved colloidal stabilities. Metal-ion doping has been proven to have a robust influence on the electronic band structure, PL behavior, and charge carrier recombination dynamics. Thus, in this perspective, we summarize the recent progress of the significant impact of metal cation doping on the optical properties, including the PL enhancement of CsPbCl3, CsPbBr3, and CsPbI3 perovskite NCs. Moreover, we shed light on the mechanism behind such improved properties. We conclude by recommending possible aspects and strategies to be further explored and considered for better utilization of these doped NCs in thin-film optoelectronic and energy conversion devices.

    更新日期:2020-01-14
  • Ultrafast excited-state proton transfer dynamics in dihalogenated non-fluorescent and fluorescent GFP chromophores
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Cheng Chen, Liangdong Zhu, Sean A. Boulanger, Nadezhda S. Baleeva, Ivan N. Myasnyanko, Mikhail S. Baranov, Chong Fang

    Green fluorescent protein (GFP) has enabled a myriad of bioimaging advances due to its photophysical and photochemical properties. To deepen the mechanistic understanding of such light-induced processes, novel derivatives of GFP chromophore p-HBDI were engineered by fluorination or bromination of the phenolic moiety into superphotoacids, which efficiently undergo excited-state proton transfer (ESPT) in aqueous solution within the short lifetime of the excited state, as opposed to p-HBDI where efficient ESPT is not observed. In addition, we tuned the excited-state lifetime from picoseconds to nanoseconds by conformational locking of the p-HBDI backbone, essentially transforming the nonfluorescent chromophores into highly fluorescent ones. The unlocked superphotoacids undergo a barrierless ESPT without much solvent activity, whereas the locked counterparts exhibit two distinct solvent-involved ESPT pathways. Comparative analysis of femtosecond transient absorption spectra of these unlocked and locked superphotoacids reveals that the ESPT rates adopt an “inverted” kinetic behavior as the thermodynamic driving force increases upon locking the backbone. Further experimental and theoretical investigations are expected to shed more light on the interplay between the modified electronic structure (mainly by dihalogenation) and nuclear motions (by conformational locking) of the functionalized GFP derivatives (e.g., fluorescence on and off).

    更新日期:2020-01-14
  • Analytical classical density functionals from an equation learning network
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-14
    S.-C. Lin, G. Martius, M. Oettel

    We explore the feasibility of using machine learning methods to obtain an analytic form of the classical free energy functional for two model fluids, hard rods and Lennard–Jones, in one dimension. The equation learning network proposed by Martius and Lampert [e-print arXiv:1610.02995 (2016)] is suitably modified to construct free energy densities which are functions of a set of weighted densities and which are built from a small number of basis functions with flexible combination rules. This setup considerably enlarges the functional space used in the machine learning optimization as compared to the previous work [S.-C. Lin and M. Oettel, SciPost Phys. 6, 025 (2019)] where the functional is limited to a simple polynomial form. As a result, we find a good approximation for the exact hard rod functional and its direct correlation function. For the Lennard–Jones fluid, we let the network learn (i) the full excess free energy functional and (ii) the excess free energy functional related to interparticle attractions. Both functionals show a good agreement with simulated density profiles for thermodynamic parameters inside and outside the training region.

    更新日期:2020-01-14
  • Turing instability conditions in confined systems with an effective position-dependent diffusion coefficient
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    G. Chacón-Acosta, M. Núñez-López, I. Pineda

    We study a reaction-diffusion system within a long channel in the regime in which the projected Fick-Jacobs-Zwanzig operator for confined diffusion can be used. We found that under this approximation, Turing instability conditions can be modified due to the channel geometry. The dispersion relation, range of unstable modes where pattern formation occurs, and spatial structure of the patterns itself change as functions of the geometric parameters of the channel. This occurs for the three channels analyzed, for which the values of the projected operators can be found analytically. For the reaction term, we use the well-known Schnakenberg kinetics.

    更新日期:2020-01-14
  • Large-scale excited-state calculation using dynamical polarizability evaluated by divide-and-conquer based coupled cluster linear response method
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    Takeshi Yoshikawa, Jyunya Yoshihara, Hiromi Nakai

    This study attempted to propose an efficient scheme at the coupled cluster linear response (CCLR) level to perform large-scale excited-state calculations of not only local excitations but also nonlocal ones such as charge transfers and transitions between delocalized orbitals. Although standard applications of fragmentation techniques to the excited-state calculations brought about the limitations that could only deal with local excitations, this study solved the problem by evaluating the excited states as the poles of dynamical polarizability. Because such an approach previously succeeded at the time-dependent density functional theory level [H. Nakai and T. Yoshikawa, J. Chem. Phys. 146, 124123 (2017)], this study was considered as an extension to the CCLR level. To evaluate the dynamical polarizability at the CCLR level, we revisited three equivalent formulas, namely, coupled-perturbed self-consistent field (CPSCF), random phase approximation (RPA), and Green’s function (GF). We further extended these formulas to the linear-scaling methods based on the divide-and-conquer (DC) technique. We implemented the CCLR with singles and doubles (CCSDLR) program for the six schemes, i.e., the standard and DC-type CPSCF, RPA, and GF. Illustrative applications of the present methods demonstrated the accuracy and efficiency. Although the standard three treatments could exactly reproduced the conventional frequency-domain CCSDLR results, their computational costs were commonly higher than that of the conventional ones due to large amount of computations for individual frequencies of the external electric field. The DC-type treatments, which approximately reproduced the conventional results, could achieve quasilinear scaling computational costs. Among them, DC-GF was found to exhibit the best performance.

    更新日期:2020-01-14
  • Adaptive Markov state model estimation using short reseeding trajectories
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    Hongbin Wan, Vincent A. Voelz

    In the last decade, advances in molecular dynamics (MD) and Markov State Model (MSM) methodologies have made possible accurate and efficient estimation of kinetic rates and reactive pathways for complex biomolecular dynamics occurring on slow time scales. A promising approach to enhanced sampling of MSMs is to use “adaptive” methods, in which new MD trajectories are “seeded” preferentially from previously identified states. Here, we investigate the performance of various MSM estimators applied to reseeding trajectory data, for both a simple 1D free energy landscape and mini-protein folding MSMs of WW domain and NTL9(1–39). Our results reveal the practical challenges of reseeding simulations and suggest a simple way to reweight seeding trajectory data to better estimate both thermodynamic and kinetic quantities.

    更新日期:2020-01-14
  • Dissipation and dynamics in ultrafast intersystem crossings
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    Michel van Veenendaal

    The effects of dynamics and dissipation on ultrafast intersystem crossings are studied for a dissipative two-level system coupled to a local vibronic mode. A method of amplitude damping of the wave packet is presented that accounts better for the position of the wave packet and avoids spurious transitions between potential wells. It is demonstrated that Fermi’s golden rule, the typical semiquantitative approach to extract population transfer rates from potential landscapes, only holds under limited conditions. Generally, the effects of dynamics and dissipation lead to deviations from the expected exponential population transfer, strong changes in transfer times and total population transfer, and significant recurrence or “spill back” of the wave packet.

    更新日期:2020-01-14
  • Use of the complete basis set limit for computing highly accurateab initiodipole moments
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    Eamon K. Conway, Iouli E. Gordon, Oleg L. Polyansky, Jonathan Tennyson

    Calculating dipole moments with high-order basis sets is generally only possible for the light molecules, such as water. A simple, yet highly effective strategy of obtaining high-order dipoles with small, computationally less expensive basis sets is described. Using the finite field method for computing dipoles, energies calculated with small basis sets can be extrapolated to produce dipoles that are comparable to those obtained in high order calculations. The method reduces computational resources by approximately 50% (allowing the calculation of reliable dipole moments for larger molecules) and simultaneously improves the agreement with experimentally measured infrared transition intensities. For atmospherically important molecules, which are typically too large to consider the use of large basis sets, this procedure will provide the necessary means of improving calculated spectral intensities by several percent.

    更新日期:2020-01-14
  • Quantum momentum distribution and quantum entanglement in the deep tunneling regime
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    Yantao Wu, Roberto Car

    In this paper, we consider the momentum operator of a quantum particle directed along the displacement of two of its neighbors. A modified open-path path integral molecular dynamics is presented to sample the distribution of this directional momentum distribution, where we derive and use a new estimator for this distribution. Variationally enhanced sampling is used to obtain this distribution for an example molecule, malonaldehyde, in the very low temperature regime where deep tunneling happens. We find no secondary feature in the directional momentum distribution and that its absence is due to quantum entanglement through a further study of the reduced density matrix.

    更新日期:2020-01-14
  • Coarse-grained simulations of diffusion controlled release of drugs from neutral nanogels: Effect of excluded volume interactions
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-08
    José Alberto Maroto-Centeno, Manuel Quesada-Pérez

    The primary goal of this work is to assess the effect of excluded volume interactions on the diffusion controlled release of drug molecules from a spherical, neutral, inert, and cross-linked device of nanometric size. To this end, coarse-grained simulations of the release process were performed. In this way, the inner structure and topology of the polymer network can be explicitly taken into account as well. Our in silico experiments reveal that the boundary condition of constant surface concentration is not appropriate for nanogels. In particular, the predictions based on the perfect sink condition clearly overestimate the fraction of drug released. In addition, these simulations provide values for the release exponent that depends on both the diameter of drug molecules and the number of drug molecules loaded in the matrix, which clearly contrasts with the classical prediction of a constant release exponent. Consequently, the widely used classification of drug release mechanisms based on this kinetic exponent must be extended to include new situations.

    更新日期:2020-01-14
  • Transforming high-dimensional potential energy surfaces into a canonical polyadic decomposition using Monte Carlo methods
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-09
    Markus Schröder

    A Monte Carlo method is proposed for transforming high-dimensional potential energy surfaces evaluated on discrete grid points into a sum-of-products form, more precisely into a Canonical Polyadic Decomposition form. To this end, a modified existing ansatz based on the alternating least squares method is used, in which numerically exact integrals are replaced with Monte Carlo integrals. This largely reduces the numerical cost by avoiding the evaluation of the potential on all grid points and allows the treatment of surfaces with many degrees of freedom. Calculations on the 15D potential of the protonated water dimer (Zundel cation) in a sum-of-products form are presented and compared to the results obtained in a previous work [M. Schröder and H.-D. Meyer, J. Chem. Phys. 147, 064105 (2017)], where a sum-of-products form of the potential was obtained in the Tucker format.

    更新日期:2020-01-14
  • Algorithms to apply dihedral-angle constraints in molecular or stochastic dynamics simulations
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-09
    Maria Pechlaner, Wilfred F. van Gunsteren

    Various algorithms to apply dihedral-angle constraints in molecular dynamics or stochastic dynamics simulations of molecular systems are presented, investigated, and tested. They use Cartesian coordinates and determine the Lagrangian multipliers necessary for maintaining the constraints iteratively. The most suitable algorithm to maintain a dihedral-angle constraint is numerically compared to the alternative to use distance constraints to this end. It can easily be used to obtain a potential of mean force along a dihedral-angle coordinate.

    更新日期:2020-01-14
  • Bayesian counting of photobleaching steps with physical priors
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-09
    Jon Garry, Yuchong Li, Brandon Shew, Claudiu C. Gradinaru, Andrew D. Rutenberg

    Counting fluorescence photobleaching steps is commonly used to infer the number n0 of monomeric units of individual oligomeric protein complexes or misfolded protein aggregates. We present a principled Bayesian approach for counting that incorporates the statistics of photobleaching. Our physics-based prior leads to a simple and efficient numerical scheme for maximum a posteriori probability (MAP) estimates of the initial fluorophore number n^0. Our focus here is on using a calibration to precisely estimate n^0, though our approach can also be used to calibrate the photophysics. Imaging noise increases with n^0, while bias is often introduced by temporal averaging. We examine the effects of fluorophore number n^0 of the oligomer or aggregate, lifetime photon yield μeff of an individual fluorophore, and exposure time Δt of each image frame in a time-lapse experiment. We find that, in comparison with standard ratiometric approaches or with a “change-point” step-counting algorithm, our MAP approach is both more precise and less biased.

    更新日期:2020-01-14
  • An accelerated linear method for optimizing non-linear wavefunctions in variational Monte Carlo
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    Iliya Sabzevari, Ankit Mahajan, Sandeep Sharma

    Although the linear method is one of the most robust algorithms for optimizing nonlinearly parametrized wavefunctions in variational Monte Carlo, it suffers from a memory bottleneck due to the fact that at each optimization step, a generalized eigenvalue problem is solved in which the Hamiltonian and overlap matrices are stored in memory. Here, we demonstrate that by applying the Jacobi-Davidson algorithm, one can solve the generalized eigenvalue problem iteratively without having to build and store the matrices in question. The resulting direct linear method greatly lowers the cost and improves the scaling of the algorithm with respect to the number of parameters. To further improve the efficiency of optimization for wavefunctions with a large number of parameters, we use the first order method AMSGrad far from the minimum as it is very inexpensive and only switch to the direct linear method near the end of the optimization where methods such as AMSGrad have long convergence tails. We apply this improved optimizer to wavefunctions with real and orbital space Jastrow factors applied to a symmetry-projected generalized Hartree-Fock reference. Systems addressed include atomic systems such as beryllium and neon, molecular systems such as the carbon dimer and iron(ii) porphyrin, and model systems such as the Hubbard model and hydrogen chains.

    更新日期:2020-01-14
  • Compressed intramolecular dispersion interactions
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    Cameron J. Mackie, Jérôme F. Gonthier, Martin Head-Gordon

    The feasibility of the compression of localized virtual orbitals is explored in the context of intramolecular long-range dispersion interactions. Singular value decomposition (SVD) of coupled cluster doubles amplitudes associated with the dispersion interactions is analyzed for a number of long-chain systems, including saturated and unsaturated hydrocarbons and a silane chain. Further decomposition of the most important amplitudes obtained from these SVDs allows for the analysis of the dispersion-specific virtual orbitals that are naturally localized. Consistent with previous work on intermolecular dispersion interactions in dimers, it is found that three important geminals arise and account for the majority of dispersion interactions at the long range, even in the many body intramolecular case. Furthermore, it is shown that as few as three localized virtual orbitals per occupied orbital can be enough to capture all pairwise long-range dispersion interactions within a molecule.

    更新日期:2020-01-14
  • Intermediate state representation approach to physical properties of molecular electron-detached states. I. Theory and implementation
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    Adrian L. Dempwolff, Alexander C. Paul, Alexandra M. Belogolova, Alexander B. Trofimov, Andreas Dreuw

    The third-order non-Dyson algebraic-diagrammatic construction approach to the electron propagator [IP-ADC(3)] is extended using the intermediate state representation (ISR) formalism, allowing the wave functions and properties of molecular states with detached electron to be studied. The second-order ISR equations [ISR(2)] for the one-particle (transition) density matrix have been derived and implemented in the Q-CHEM program. The approach is completely general and enables evaluation of arbitrary one-particle operators and interpretation of electron detachment processes in terms of density-based quantities. The IP-ADC(3)/ISR(2) equations were implemented for Ŝz-adapted intermediate states, allowing open-shell molecules to be studied using unrestricted Hartree-Fock references. As a first test for computations of ground state properties, dipole moments of various closed- and open-shell molecules have been computed by means of electron detachment from the corresponding anions. The results are in good agreement with experimental data. The potential of IP-ADC(3)/ISR(2) for the interpretation of photoelectron spectra is demonstrated for the galvinoxyl free radical.

    更新日期:2020-01-14
  • Shadow Hamiltonian in classical NVE molecular dynamics simulations: A path to long time stability
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    K. D. Hammonds, D. M. Heyes

    The shadow energy, Es, is the conserved quantity in microcanonical ensemble (NVE) molecular dynamics simulations carried out with the position Verlet central-difference algorithm. A new methodology for calculating precise and accurate values of Es is presented. It is shown for the first time that Es rather than E is constant during structural changes occurring within a supercooled liquid. It is also explained how to prepare and conduct microsecond range bulk-phase NVE simulations with essentially zero energy drift without the need for thermostating. The drift is analyzed with block averaging and new drift functions of the shadow energy. With such minimal drift, extremely small and accurate standard errors in the mean for quantities like Es, E, and temperature, T, can be obtained. Values of the standard error for Es of ≈10−10 in molecule-based reduced units can be routinely achieved for simulations of 108 time steps. This corresponds to a simulation temperature drift of ≈10−6 K/μs, six orders of magnitude smaller than generally considered to be acceptable for protein simulations. We also show for the first time how these treatments can be extended with no loss of accuracy to polyatomic systems with both flexible degrees of freedom and arbitrary geometric constraints imposed via the SHAKE algorithm. As a bonus, estimates of simulation-average kinetic and total energies from high order velocity expressions can be obtained to a good approximation from 2nd order velocities and the average mean square force (for polyatomics, this refers to per site, including any constraint forces).

    更新日期:2020-01-14
  • Binuclear Mn oxo complex as a self-contained photocatalyst in water-splitting cycle: Role of additional Mn oxides as a buffer of electrons and protons
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    Kentaro Yamamoto, Kazuo Takatsuka

    We theoretically propose a photoinduced water-splitting cycle catalyzed by a binuclear Mn oxo complex. In our “bottom-up approach” to this problem, we once proposed a working minimal model of water-splitting cycle in terms of a mononuclear Mn oxo complex as a catalyst along with water clusters [K. Yamamoto and K. Takatsuka, Phys. Chem. Chem. Phys. 20, 6708 (2018)]. However, this catalyst is not self-contained in that the cycle additionally needs buffering molecules for electrons and protons in order to reload the Mn complex with electrons and protons, which are lost by photoinduced charge separation processes. We here show that a binuclear Mn oxo complex works as a self-contained photocatalyst without further assistant of additional reagents and propose another catalytic cycle in terms of this photocatalyst. Besides charge separation and proton relay transfer, the proposed cycle consists of other fundamental chemical dynamics including electron–proton reloading, radical relay-transfer, and Mn reduction. The feasibility of the present water-splitting cycle is examined by means of full dimensional nonadiabatic electron–wavepacket dynamics based on multireference electronic wavefunctions and energy profiles estimated with rather accurate quantum chemical methods for all the metastable states appearing in the cycle.

    更新日期:2020-01-14
  • Linear scaling perturbative triples correction approximations for open-shell domain-based local pair natural orbital coupled cluster singles and doubles theory [DLPNO-CCSD(T0/T)]
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-10
    Yang Guo, Christoph Riplinger, Dimitrios G. Liakos, Ute Becker, Masaaki Saitow, Frank Neese

    The coupled cluster method with single-, double-, and perturbative triple excitations [CCSD(T)] is considered to be one of the most reliable quantum chemistry theories. However, the steep scaling of CCSD(T) has limited its application to small or medium-sized systems for a long time. In our previous work, the linear scaling domain based local pair natural orbital CCSD variant (DLPNO-CCSD) has been developed for closed-shell and open-shell. However, it is known from extensive benchmark studies that triple-excitation contributions are important to reach chemical accuracy. In the present work, two linear scaling (T) approximations for open-shell DLPNO-CCSD are implemented and compared: (a) an algorithm based on the semicanonical approximation, in which off-diagonal Fock matrix elements in the occupied space are neglected [referred to as DLPNO-(T0)]; and (b) an improved algorithm in which the triples amplitudes are computed iteratively [referred to as DLPNO-(T)]. This work is based on the previous open-shell DLPNO-CCSD algorithm [M. Saitow et al., J. Chem. Phys. 146, 164105 (2017)] as well as the iterative (T) correction for closed-shell systems [Y. Guo et al., J. Chem. Phys. 148, 011101 (2018)]. Our results show that the new open-shell perturbative corrections, DLPNO-(T0/T), can predict accurate absolute and relative correlation energies relative to the canonical reference calculations with the same basis set. The absolute energies from DLPNO-(T) are significantly more accurate than those of DLPNO-(T0). The additional computational effort of DLPNO-(T) relative to DLPNO-(T0) is a factor of 4 on average. We report calculations on systems with more than 4000 basis functions.

    更新日期:2020-01-14
  • Evaluation of the AMOEBA force field for simulating metal halide perovskites in the solid state and in solution
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    P. V. G. M. Rathnayake, Stefano Bernardi, Asaph Widmer-Cooper

    In this work, we compare the existing nonpolarizable force fields developed to study the solid or solution phases of hybrid organic-inorganic halide perovskites with the AMOEBA polarizable force field. The aim is to test whether more computationally expensive polarizable force fields like AMOEBA offer better transferability between solution and solid phases, with the ultimate goal being the study of crystal nucleation, growth, and other interfacial phenomena involving these ionic compounds. In the context of hybrid perovskites, AMOEBA force field parameters already exist for several elements in solution, and we decided to leave them unchanged and to only parameterize the missing ones (Pb2+ and CH3NH3+ ions) in order to maximize transferability and avoid overfitting to the specific examples studied here. Overall, we find that AMOEBA yields accurate hydration free energies (within 5%) for typical ionic species while showing the correct ordering of stability for the different crystal polymorphs of CsPbI3 and CH3NH3PbI3. Although the existing parameters do not accurately reproduce all transition temperatures and lattice parameters, AMOEBA offers better transferability between solution and solid states than existing nonpolarizable force fields.

    更新日期:2020-01-14
  • Orbital localization error of density functional theory in shear properties of vanadium and niobium
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Yi X. Wang, Hua Y. Geng, Q. Wu, Xiang R. Chen

    It is believed that the density functional theory (DFT) describes most elements with s, p, and d orbitals very well, except some materials that have strongly localized and correlated valence electrons. In this work, we find that the widely employed exchange-correlation (XC) functionals, including local-density approximation (LDA), generalized gradient approximation (GGA), and meta-GGA, underestimate the shear modulus and phase stability of V and Nb greatly. The advanced hybrid functional that is usually better for correlated systems, on the other hand, completely fails in these two simple metals. This striking failure is revealed due to the orbital localization error in GGA, which is further deteriorated by hybrid functionals. This observation is corroborated by a similar failure of DFT+U and van der Waals functionals when applied to V and Nb. To remedy this problem, a semiempirical approach of DFT+J is proposed, which can delocalize electrons by facilitating the on-site exchange. Furthermore, it is observed that including density derivatives slightly improves the performance of the semilocal functionals, with meta-GGA outperforms GGA, and the latter is better than LDA. This discovery indicates the possibility and necessity to include higher-order density derivatives beyond the Laplacian level for the purpose of removing the orbital localization error (mainly from d orbitals) and delocalization error (mainly from s and p orbitals) completely in V and Nb so that a better description of their electronic structures is achieved. The same strategy can be applied to the other d electron system and f electron system.

    更新日期:2020-01-14
  • Quantum mechanical/molecular mechanical trajectory surface hopping molecular dynamics simulation by spin-flip time-dependent density functional theory
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Noriyuki Minezawa, Takahito Nakajima

    This paper presents the nonadiabatic molecular dynamics simulation in the solution phase using the spin-flip time-dependent density functional theory (SF-TDDFT). Despite the single-reference level of theory, the SF-TDDFT method can generate the correct topology of S0/S1 crossing points, thus providing a natural S1 → S0 nonadiabatic transition. We extend the gas-phase trajectory surface hopping simulation with the SF-TDDFT [N. Minezawa and T. Nakajima, J. Chem. Phys. 150, 204120 (2019)] to the hybrid quantum mechanical/molecular mechanics (QM/MM) scheme. To this end, we modify the code to evaluate the electrostatic interaction between the QM and MM atoms and to extract the classical MM energy and forces from the MM program package. We apply the proposed method to the photoisomerization reaction of aqueous E-azomethane and anionic green fluorescent protein chromophore in water and compare the results with those of the previous simulation studies based on the multireference methods.

    更新日期:2020-01-14
  • The nuclear Overhauser Effect (NOE) as a tool to study macromolecular confinement: Elucidation and disentangling of crowding and encapsulation effects
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Philipp Honegger, Othmar Steinhauser

    We propose a methodology to capture short-lived but biophysically important contacts of biomacromolecules using the biomolecule-water nuclear Overhauser effect as an indirect microscope. Thus, instead of probing the direct correlation with the foreign biomolecule, we detect its presence by the disturbance it causes in the surrounding water. In addition, this information obtained is spatially resolved and can thus be attributed to specific sites. We extend this approach to the influence of more than one change in chemical environment and show a methodological way of resolution. This is achieved by taking double differences of corresponding σNOE/σROE ratios of the systems studied and separating specific, unspecific, and intermediate influence. While applied to crowding and encapsulation in this study, this method is generally suitable for any combination of changes in chemical environment.

    更新日期:2020-01-14
  • Electrostatic interactions between spheroidal dielectric particles
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Ivan N. Derbenev, Anatoly V. Filippov, Anthony J. Stace, Elena Besley

    Theory is developed to address the significant problem of electrostatic interactions between charged polarizable dielectric spheroids. The electrostatic force is defined by particle dimensions and charge, dielectric constants of the interacting particles and medium, and the interparticle separation distance; and it is expressed in the form of an integral over the particle surface. The switching behavior between like charge repulsion and attraction is demonstrated as depending on the ratio of the major and minor axes of spheroids. When the major and minor axes are equal, the theory yields a solution equivalent to that obtained for spherical particles. Limiting cases are presented for nonpolarizable spheroids, which describe the electrostatic behavior of charged rods, discs, and point charges. The developed theory represents an important step toward comprehensive understanding of direct interactions and mechanisms of electrostatically driven self-assembly processes.

    更新日期:2020-01-14
  • Techniques for high-performance construction of Fock matrices
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Hua Huang, C. David Sherrill, Edmond Chow

    This paper presents techniques for Fock matrix construction that are designed for high performance on shared and distributed memory parallel computers when using Gaussian basis sets. Four main techniques are considered. (1) To calculate electron repulsion integrals, we demonstrate batching together the calculation of multiple shell quartets of the same angular momentum class so that the calculation of large sets of primitive integrals can be efficiently vectorized. (2) For multithreaded summation of entries into the Fock matrix, we investigate using a combination of atomic operations and thread-local copies of the Fock matrix. (3) For distributed memory parallel computers, we present a globally accessible matrix class for accessing distributed Fock and density matrices. The new matrix class introduces a batched mode for remote memory access that can reduce the synchronization cost. (4) For density fitting, we exploit both symmetry (of the Coulomb and exchange matrices) and sparsity (of 3-index tensors) and give a performance comparison of density fitting and the conventional direct calculation approach. The techniques are implemented in an open-source software library called GTFock.

    更新日期:2020-01-14
  • Timescale prediction of complex multi-barrier pathways using flux sampling molecular dynamics and 1D kinetic integration: Application to cellulose dehydration
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Pierre-Louis Valdenaire, Roland J. M. Pellenq, Franz J. Ulm, Adri C. T. van Duin, Jean-Marc Leyssale

    Reactive molecular dynamics (MD) simulations, especially those employing acceleration techniques, can provide useful insights on the mechanism underlying the transformation of buried organic matter, yet, so far, it remains extremely difficult to predict the time scales associated with these processes at moderate temperatures (i.e., when such time scales are considerably larger than those accessible to MD). We propose here an accelerated method based on flux sampling and kinetic integration along a 1D order parameter that can considerably extend the accessible time scales. We demonstrate the utility of this technique in an application to the dehydration of crystalline cellulose at temperatures ranging from 1900 K to 1500 K. The full decomposition is obtained at all temperatures apart from T = 1500 K, showing the same distribution of the main volatiles (H2O, CO, and CO2) as recently obtained using replica exchange molecular dynamics. The kinetics of the process is well fitted with an Arrhenius law with Ea = 93 kcal/mol and k0 = 9 × 1019 s−1, which are somehow larger than experimental reports. Unexpectedly, the process seems to considerably slow down at lower temperatures, severely departing from the Arrhenius regime, probably because of an inadequate choice of the order parameter. Nevertheless, we show that the proposed method allows considerable time sampling at low temperatures compared to conventional MD.

    更新日期:2020-01-14
  • Parameter-free coordination numbers for solutions and interfaces
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-13
    Ruben Staub, Stephan N. Steinmann

    Coordination numbers are among the central quantities to describe the local environment of atoms and are thus used in various applications such as structure analysis, fingerprints, and parameters. Yet, there is no consensus regarding a practical algorithm, and many proposed methods are designed for specific systems. In this work, we propose a scale-free and parameter-free algorithm for nearest neighbor identification. This algorithm extends the powerful Solid-Angle based Nearest-Neighbor (SANN) framework to explicitly include local anisotropy. As such, our Anisotropically corrected SANN (ASANN) algorithm provides with a fast, robust, and adaptive method for computing coordination numbers. The ASANN algorithm is applied to flat and corrugated metallic surfaces to demonstrate that the expected coordination numbers are retrieved without the need for any system-specific adjustments. The same applies to the description of the coordination numbers of metal atoms in AuCu nanoparticles, and we show that ASANN based coordination numbers are well adapted for automatically counting neighbors and the establishment of cluster expansions. Analysis of classical molecular dynamics simulations of an electrified graphite electrode reveals a strong link between the coordination number of Cs+ ions and their position within the double layer, a relation that is absent for Na+, which keeps its first solvation shell even close to the electrode.

    更新日期:2020-01-14
  • Intermediate state representation approach to physical properties of molecular electron-detached states. II. Benchmarking
    J. Chem. Phys. (IF 2.997) Pub Date : 2020-01-14
    Adrian L. Dempwolff, Alexander C. Paul, Alexandra M. Belogolova, Alexander B. Trofimov, Andreas Dreuw

    The third-order algebraic-diagrammatic construction method for studies of electron detachment processes within the electron propagator framework [IP-ADC(3)] was extended to treat the properties of molecular states with a detached electron using the intermediate state representation (ISR) formalism. The second-order ISR(2) equations for the one-particle (transition) density matrix have been derived and implemented as an extension of the IP-(U)ADC(3) method available in the Q-CHEM program. As a first systematic test of the present IP-(U)ADC(3)/ISR(2) method, the dipole moments of various electronic states of closed- and open-shell molecules have been computed and compared to full configuration interaction (FCI) results. The present study employing FCI benchmarks also provides the first rigorous estimates for the accuracy of electron detachment energies obtained using the IP-ADC(3) method.

    更新日期:2020-01-14
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