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  • Concerted-asynchronous reaction path of the excited-state double proton transfer in the 7-azaindole homodimer and 6H-indolo[2,3-b]quinoline/7-azaindole heterodimer
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-13
    Shohei Yamazaki

    Reaction path of the excited-state double proton transfer (ESDPT) in the homodimer of 7-azaindole (7AI2 homodimer) and heterodimer of 6H-indolo[2,3-b]quinoline and 7-azaindole (6HIQ-7AI heterodimer) is computationally studied by means of intrinsic reaction coordinate (IRC) calculations. The IRC path determined at the TDDFT level predicts the concerted-asynchronous mechanism for the ESDPT in 6HIQ-7AI as well as in 7AI2, where the N-H⋯⋯N hydrogen bonds exhibit asymmetric structures along the reaction path with a single energy barrier. The IRC calculations at the CIS level, however, exhibits a local minimum for single-proton-transferred intermediate, suggesting the stepwise mechanism. Single-point energy calculations at the RI-CC2 level reproduce the TDDFT results, but do not the CIS results. On the basis of potential-energy profiles calculated against intermolecular distance, the discrepancy between the TDDFT and CIS methods is likely attributed to the underestimation of intermolecular interaction energy in the latter method due to the lack of dynamical electron correlation.

    更新日期:2017-11-14
  • 6.2 μm Spectrum and 6-Dimensional Morphed Potentials of OC-H2O
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-13
    Luis A. Rivera-Rivera, Blake A. McElmurry, Kevin W. Scott, Sean D. Springer, Robert R. Lucchese, John W. Bevan, Igor I. Leonov, Laurent H. Coudert

    Rovibrational transitions associated with tunneling states in the ν5 (water bending) vibration of the OC-H2O complex have been recorded using a supersonic jet mode-hop free quantum cascade laser spectrometer at 6.2 μm. Analysis of the resulting spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data accounting for Coriolis coupling. The theoretical basis of morphing a 5-D frozen monomers potential was initially developed and then extended to two 6-D morphed potentials. A combination of these spectroscopic results and previous rovibrational data for the ν5 vibration in OC-D2O are then used to generate a 6-D morphed potential surface for the intermolecular and the water bending vibrations. An alternative 6-D morphed potential of the intermolecular and the ν3 (CO stretching) vibrations was also generated. These determined morphed potentials then formed the basis for modeling the dynamics of the complex and prediction of accurate intermolecular rovibrational frequencies of the complex.

    更新日期:2017-11-14
  • Predicting Glass-to-Glass and Liquid-to-Liquid Phase Transitions in Supercooled Water using Classical Nucleation Theory
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-13
    Robert F. Tournier

    Glass-to-glass and liquid-to-liquid phase transitions are observed in bulk and confined water, with or without applied pressure. They result from the competition of two liquid phases separated by an enthalpy difference depending on temperature. The classical nucleation equation of these phases is completed by this quantity existing at all temperatures, a pressure contribution, and an enthalpy excess. This equation leads to two homogeneous nucleation temperatures in each liquid phase; the first one (Tn- below Tm) being the formation temperature of an “ordered” liquid phase and the second one corresponding to the overheating temperature (Tn+ above Tm). Thermodynamic properties, double glass transition temperatures, sharp enthalpy and volume changes are predicted in agreement with experimental results. The first-order transition line at TLL=0.833×Tm between fragile and strong liquids joins two critical points. Glass phase above Tg becomes “ordered” liquid phase disappearing at TLL at low pressure and at Tn+=1.302×Tm at high pressure.

    更新日期:2017-11-13
  • Tolman’s length and limiting supersaturation of vapor
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-13
    Nikolay V. Alekseechkin

    The classical Kelvin formula for the equilibrium vapor pressure over a droplet of radius R R is extended to small radii and vapor non-ideality, from where the limiting supersaturation condition is obtained by relating the point R=0 R = 0 to the value of limiting (spinodal) supersaturation of vapor. The analysis of different dependences of the Tolman length on radius, δ(R) δ ( R ) , obeying this condition suggests that (i) the value of δ(0) δ ( 0 ) is positive and the function δ(R) δ ( R ) decreases with increasing radius; (ii) the curvature effect (the dependence of surface tension on radius) in the nucleation region is determined by the value of δ(0) δ ( 0 ) . At the same time, this effect is weakly sensitive to the form of the function δ(R) δ ( R ) and insensitive to its asymptotic value δ∞ δ ∞ .

    更新日期:2017-11-13
  • Binding affinity of the L-742,001 inhibitor to the endonuclease domain of A/H1N1/PA influenza virus variants: Molecular simulation approaches
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-11
    Hung Nguyen, Hoang Linh Nguyen, Huynh Quang Linh, Minh Tho Nguyen

    The steered molecular dynamics (SMD), molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) and free energy perturbation (FEP) methods were used to determine the binding affinity of the L-742,001 inhibitor to the endonuclease domain of the A/H1N1/PA influenza viruses (including wild type (WT) and three mutations I79L, E119D and F105S for both pH1N1 PA and PR8 PA viruses). Calculated results showed that the L-742,001 inhibitor not only binds to the PR8 PAs (1934 A influenza virus) better than to the pH1N1 PAs (2009 A influenza virus) but also more strongly interacts with the WT endonuclease domain than with three mutant variants for both pH1N1 PA and PR8 PA viruses. The binding affinities obtained by the SMD, MM-PBSA and FEP methods attain high correlation with available experimental data. Here the FEP method appears to provide a more accurate determination of the binding affinity than the SMD and MM-PBSA counterparts.

    更新日期:2017-11-13
  • Excited State Properties of 2'-Hydroxychalcone Analogues Functionalized with a Diene Moiety Studied by Steady State and Laser Flash Photolysis
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-11
    Yukino Shinozaki, Minoru Yamaji, Tatsuo Arai

    2'-Hydroxychalcone (HC) analogues 1 and 2 having a diene part tethering the phenyl and naphthyl chromophores, respectively, were prepared, and their photochemical and photophysical properties were studied. Fluorescence from these compounds was absent in solution and the solid state. Based on the results obtained upon steady state and laser flash photolyses, compound 2 was found to be substantially stable on photoirradiation without undergoing intersystem crossing to the triplet state whereas compounds 1 showed transient absorption due to the triplet tautomer. The deactivation processes in the excited states were discussed by considering energetic reaction diagrams for the corresponding tautomers and isomers.

    更新日期:2017-11-13
  • MCTDH Study on the Reactive Scattering of the Cl + HD Reaction based on the Neural-Networks Potential Energy Surface ☆
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-11
    Qingyong Meng

    To study the dynamics resonances of the Cl + HD reaction which was proposed to proceed via abstraction mechanism with no clear resonances, we perform dynamics calculations by the multiconfiguration time-dependent Hartree (MCTDH) method based on recently developed neural-networks potential energy surface (Science347 (2015), 60). The HD molecule in v=0 v = 0 (GS), v=1 v = 1 (EX1), v=2 v = 2 (EX2), and v=3 v = 3 (EX3) states is used for the reactant. For GS, no distinctive resonance peak is found, while for EX1 two distinctive peaks at kinetics energies of 0.11 0.11 and 0.17 0.17 eV are investigated. These resonance peaks are well consistent with the previous results (Science347 (2015), 60). Moreover, the present MCTDH calculations predict well-marked resonance peaks at 0.04,0.05,0.07 0.04 , 0.05 , 0.07 , and 0.10 0.10 eV for EX2 and EX3, which indicates that anticipation of the chemical bond softening model (Science327 (2010), 1501) is confirmed in this work.

    更新日期:2017-11-13
  • Molecular dynamics simulation of the thermosensitivity of the human connexin 26 hemichannel
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-09
    Hadi Alizadeh, Jamal Davoodi, Carsten Zeilinger, Hashem Rafii-Tabar

    Connexin hemichannels mediate cytoplasm and extracellular milieu communication by exchanging a variety of cytoplasmic molecules and ions. These hemichannels can be regulated by external stimuli such as mechanical stress, applied voltage, pH and temperature changes. Although there are many studies on structures and functions of connexin 26 in contexts of pH, ion concentration and voltage, employing computational methods, no such study has been performed so far involving temperature changes. In this study, using molecular dynamics simulation, we investigate thermosensitivity of the human Connexin 26 hemichannel. Our results show that the channel approaches a structurally closed state at lower temperature compared to higher temperature. This is in fair agreement with experimental results that indicate channel closure at lower temperature. Furthermoer, our MD simulation results show that some regions of connexin 26 hemichannel are more sensitive to temperature compared to other regions. Whereas the intercellular half of the channel does not show any considerable response to temperature during the simulation time accessible in this study, the cytoplasmic half approaches a closed structural state at lower temperature compared to the higher temperature. Specifically, our results suggest that the cytoplasmic loop, the cytoplasmic half of the second transmembrane helix, and the N-terminus helix play a dominant role in temperature gating.

    更新日期:2017-11-10
  • Radiative decay of HeLi+(b3++)
    Chem. Phys. (IF 1.767) Pub Date : 2017-11-08
    Martina Zámečníková, Pavel Soldán

    Radiative lifetimes of the ro-vibrational bound states of HeLi+HeLi+(b3∑+b3∑+) are calculated quantum-mechanically when both bound-bound and bound-free processes are taken into account. The calculations are restricted to the initial states with low rotational quantum numbers. For the rotationless molecular ion, the shortest lifetime is 1.30×10-6s1.30×10-6s of the ground vibrational state. With increasing vibration excitations the radiative lifetimes slightly increase, but keep below 10-5s10-5s for next 17 vibrational states, then they start to increase more rapidly up to 2.41×10-2s2.41×10-2s for the highest vibrational state. The radiative lifetimes also tend to slightly prolong with increasing rotation excitations but stay on the same magnitude for the low rotational quantum numbers.

    更新日期:2017-11-10
  • A multimode-like scheme for selecting the centers of Gaussian basis functions when computing vibrational spectra
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-23
    Sergei Manzhos, Xiaogang Wang, Tucker Carrington Jr
    更新日期:2017-10-24
  • Predictive methods of some optoelectronic properties for blends based on quaternized polysulfones
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-23
    Adina Maria Dobos, Anca Filimon
    更新日期:2017-10-24
  • Quasirelativistic potential energy curves and transition dipole moments of NaRb
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-21
    M. Wiatr, P. Jasik, T. Kilich, J.E. Sienkiewicz, H. Stoll

    We report on extensive calculations of quasi-relativistic potential energy curves and, for the first time, transition dipole moments including spin-orbit and scalar-relativistic effects of the NaRb molecule. The calculated curves of the 0+ 0 + , 0- 0 - , 1, 2 and 3 molecular states correlate for large internuclear separation with the fourteen lowest atomic energies up to the Na(3s2 s 2 S1/2 S 1 / 2 )+Rb(7s2 s 2 S1/2 S 1 / 2 ) atomic limit. Several new features of the potential energy curves have been found.

    更新日期:2017-10-23
  • Dynamic interference in the resonance-enhanced multiphoton ionization of hydrogen atoms by short and intense laser pulses
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-21
    Anne D. Müller, Eric Kutscher, Anton N. Artemyev, Lorenz S. Cederbaum, Philipp V. Demekhin

    Photoionization of the hydrogen atom by intense and short coherent laser pulses is investigated from first principles by a numerical solution of the time-dependent Schrödinger equation in the dipole-velocity gauge. The considered photon energies are resonant to the 1s→2p 1 s → 2 p excitation, and the pulse intensities are high enough to induce Rabi floppings. The computed resonance-enhanced two-photon ionization spectra as well as the three-photon above threshold ionization spectra exhibit pronounced multiple-peak patterns due to dynamic interference. Fingerprints of dynamic interference can also be seen directly in the radial density of the photoelectron. The impact of the variation of the pulse intensity and photon energy on the dynamic interference is investigated, and the angular distribution of the emitted electrons is analyzed in some details. The present precise numerical results confirm our previous theoretical predictions on the two-photon ionization spectra [Phys. Rev. A 86 (2012) 063412] made within a minimal few-level model.

    更新日期:2017-10-21
  • A quantum dynamical study of the photoelectron spectra and the Renner-Teller effect in BrCN and ClCN based on four-component potential energy hypersurfaces
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-12
    V.A. Tran, M. Pernpointner

    In this work we investigate the Renner-Teller effect (RTE) in the photoelectron spectra of ClCN and BrCN. The spectra were calculated by a nuclear wave packet propagation on coupled cationic Π1/2/Π3/2 Π 1 / 2 / Π 3 / 2 surfaces obtained by the four-component Fock-space coupled cluster method. The scalar relativistic, spin-orbit and electron correlation effects are consistently included in the hypersurfaces for the three internal nuclear degrees of freedom. In contrast to other approaches no coupling matrix elements involving the spin-orbit operator together with an explicit representation of the wave function were necessary. The current study extends earlier work on the RTE for the derivation of the Renner-Teller parameters c and d where only one nuclear degree of freedom was considered [J. Phys. B 46, 125101 (2013)]. The outlined procedure is especially useful for electronic structure methods that yield accurate energies but do not provide an explicit wave function representation.

    更新日期:2017-10-12
  • 183W nuclear dipole moment determined by gas-phase NMR spectroscopy
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-10
    Piotr Garbacz, Włodzimierz Makulski
    更新日期:2017-10-10
  • Controlling harmonic distributions from H2+ driven by linearly and circularly polarized laser fields
    Chem. Phys. (IF 1.767) Pub Date : 2017-10-07
    Liqiang Feng, Yi Li, Hang Liu

    The spatial distributions of the high-order harmonics from H2+ driven by the linearly and the circularly polarized laser fields have been theoretically investigated. It is found that when the molecular axis parallels to the polarized direction of the linearly polarized laser field, the contributions of the harmonics are mainly from the negative-H and the positive-H for the cases of E(t) > 0 and E(t) < 0, respectively. As the angle between the molecular axis and the linearly polarized laser field increases, the contributions of the harmonics from the negative-H are enhanced and play the main role in the harmonic spectrum. Further, with the introduction of the controlling circularly polarized laser field, the intensity enhancement of the harmonics from the positive-H can be achieved. Moreover, the contributions of the harmonics from the two-H nuclei are sensitive to the ellipticity of the laser field. Finally, the time-frequency analyses of the harmonics and the time-dependent electron locations have been given to explain the physical mechanism behind the spatial distributions of the harmonics from the two-H nuclei of H2+.

    更新日期:2017-10-08
  • Probing adsorption sites of carbon dioxide in metal organic framework of [Zn(bdc)(dpds)]n: A molecular simulation study
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-25
    Shih-I Lu, Jian-Min Liao, Xiao-Zhuang Huang, Chia-Hsun Lin, Szu-Yu Ke, Chih-Chieh Wang

    We used force-field based grand-canonical Monte Carlo simulation method and density functional theory to study adsorption characteristics of carbon dioxide (CO2) molecules in a metal-organic framework (MOF) compound, [Zn(bdc)(dpds)]n. The studied MOF include a metal ion (Zn(II)), an anion organic linker (dianion of benzene dicarboxylicacid, bdc2−) and a neutral organic linker (4,4’-dipyridyldisulfide, dpds). Results from calculated adsorption isotherms and enthalpies of adsorption agree with the experimental data. The interactions between the adsorbed CO2 and the organic linkers were examined in simulations. Calculated results show available absorption sites are surrounded by two dpds ligands in which an S-S bond as an N-N' spacer connect two pyridines. In contrast, the bdc2− ligand does not give a significant contribution to the substantial adsorption amount even though it contains the carboxylate group that provides available bonding site to CO2.

    更新日期:2017-09-29
  • The Effect of Site-Specific Spectral Densities on the High-Dimensional Exciton-Vibrational Dynamics in the FMO Complex
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-23
    Jan Schulze, Mohamed F. Shibl, Mohammed J. Al-Marri, Oliver Kühn

    The coupled exciton-vibrational dynamics of a three-site model of the FMO complex is investigated using the Multi-layer Multi-configuration Time-dependent Hartree (ML-MCTDH) approach. Emphasis is put on the effect of the spectral density on the exciton state populations as well as on the vibrational and vibronic non-equilibrium excitations. Models which use either a single or site-specific spectral densities are contrasted to a spectral density adapted from experiment. For the transfer efficiency, the total integrated Huang-Rhys factor is found to be more important than details of the spectral distributions. However, the latter are relevant for the obtained non-equilibrium vibrational and vibronic distributions and thus influence the actual pattern of population relaxation.

    更新日期:2017-09-29
  • Effects of adding LiBF4 on the glass-transition kinetics of 1,2-propanediol
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-20
    Yukio Terashima, Kiyoshi Takeda
    更新日期:2017-09-20
  • First-Principles Investigation of Decomposition and Adsorption Properties of RDX on the Surface of MgH2
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-18
    RAO Guo-Ning, YAO Miao, PENG Jin-Hua

    Surface adsorption and decomposition mechanisms of cyclotrimethylenetrinitramine (RDX) molecules on the MgH2 (110) crystal face are investigated in this paper by employing the First-Principles. With the N-NO2 bond of RDX molecules as a reference, 12 adsorption sites are considered that are vertical (V1-V6) and parallel (P1-P6) to the MgH2 (110) surface. Results show that these 12 types of adsorption of RDX molecules on the MgH2 (110) crystal face are all chemical adsorption with high heat release, where the vertical Mg-top position (V1) is the most stable adsorption configuration. In all the 12 types of chemical adsorption, RDX molecules are decomposed, through 4 mechanisms including bis-nitro mono-N-O bond rupture, mono-nitro mono-N-O bond rupture, mono-nitro bis-N-O bond rupture and mono-N-O2 bond rupture, where the V-type adsorption is due to N-O bond rupture and the P-type adsorption is due to N-NO2 bond rupture, resulting in RDX decomposition. Secondly, in proximity to the Fermi level, the density of states of the RDX molecule highly coincides with that of the MgH2 (110) crystal face, which is prone to cause orbital hybridization and RDX decomposition. Also, the density of states in proximity to the Fermi level is mainly contributed by nitro O atoms and ring N atoms of RDX, as well as Mg atoms of the MgH2 (110) crystal face, and these 3 types of atoms are also active centers for chemical adsorption and decomposition reaction. Finally, an obvious phenomenon of charge transfer is present between Mg atoms in the first layer of the MgH2 (110) crystal face and O atoms in the nitro group of RDX. Also, the charge change in O and Mg atoms in the V configuration is greater than that in the P configuration, indicating that the V configuration has stronger interaction between RDX and the MgH2 (110) crystal face, and thus RDX in the V configuration is more prone to decomposition and the V configuration represents a better adsorption mode.

    更新日期:2017-09-19
  • Adsorption of ethylene carbonate on lithium cobalt oxide thin films: A synchrotron-based spectroscopic study of the surface chemistry
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-11
    Mathias Fingerle, Thomas Späth, Natalia Schulz, René Hausbrand
    更新日期:2017-09-11
  • Cluster Formation and Percolation in Ethanol-Water mixtures
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-09
    Orsolya Gereben, László Pusztai

    Results of systematic molecular dynamics studies of ethanol-water mixtures, over the entire concentration range, were reported previously that agree with experimental X-ray diffraction data. These simulated systems are analyzed in this work to examine cluster formation and percolation, using four different hydrogen bond definitions. Percolation analyses revealed that each mixture (even the one containing 80 mol% ethanol) is above the 3D percolation threshold, with fractal dimensions, df, between 2.6 to 2.9, depending on concentration. Monotype water cluster formation was also studied in the mixtures: 3D water percolation can be found in systems with less than 40 mol% ethanol, with fractal dimensions between 2.53 and 2.84. These observations can be put in parallel with experimental data on some thermodynamic quantities, such as the excess partial molar enthalpy and entropy.

    更新日期:2017-09-10
  • IR induced photochemistry of glycolaldehyde in nitrogen matrix
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-08
    Fabrice Duvernay, Teddy Butscher, Thierry Chiavassa, Stephane Coussan
    更新日期:2017-09-08
  • The effect of varied pH on the luminescence characteristics of antibody–mercaptoacetic acid conjugated ZnS nanowires
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-08
    Madeeha Chaudhry, Malik Abdul Rehman, Asghari Gul, Raheel Qamar, Arshad Saleem Bhatti

    We demonstrate here that the effect of varied pH of the media on the photoluminescence (PL) properties of mercaptoacetic acid (MAA) and digoxin antibody (Ab) conjugated zinc sulphide (ZnS) nanowires. The charge-transfer kinetics from MAA to ZnS and vice versa showed a profound effect on the luminescence of ZnS defect states. The PL intensity of the ZnS defect states showed strong dependence on the value of pH with respect to the pKa of MAA. The carboxyl and thiol group of MAA in the protonated (pH < pKa) and deprotonated (pH > pKa) states resulted in the quenched PL intensity. While for pH ∼ pKa, the PL intensity was regained as there was equal probability of both protonated and deprotonated carboxyl and thiol groups. These findings indicated that pH of the environment is a key parameter for the use of MAA-Ab conjugated ZnS nanowires as an optical biomarker.

    更新日期:2017-09-08
  • Molecular Dynamics Simulation Study of Hydration of Uranyl Nitrate in Supercritical Water: Dissecting the Effect of Uranyl Ion Concentration from Solvent Density
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-06
    Manish Chopra, Niharendu Choudhury

    All atom molecular dynamics simulations of uranyl ions in supercritical water are used to dissect the effects of concentration of uranyl ions and density of water on various structural and dynamic properties of the solutions. The analyses of radial distribution functions as a function of concentration of the uranyl ion and water density reveal that the effect of the former on the local structure is negligible as compared to the same of the later. The number of hydration water of the uranyl ion has been observed to increase with increasing density of the water, but it decreases with the increasing concentration of the uranyl ions. The orientational distributions are observed to be independent of variation in concentration of the uranyl ion, same as the case was with water density. The translational and rotational dynamics of the water molecules have been investigated from the respective mean squared displacements and time correlation functions. Although increase of both the concentration of the uranyl ions and the density of water reduces translational diffusivity of water as well as uranyl ions, the effect of changing water density is more than that of uranyl concentrations. However, orientational relaxation of various molecular vectors of the water molecule is practically unchanged with any variation in concentration of the uranyl ions and it changes only slightly with the change in water density. Unlike at ambient condition, orientational dynamics at supercritical conditions remains virtually unchanged with the change in uranyl ion concentration.

    更新日期:2017-09-06
  • Multimodal Hyperspectral Optical Microscopy
    Chem. Phys. (IF 1.767) Pub Date : 2017-09-02
    Irina V. Novikova, Chuck R. Smallwood, Yu Gong, Dehong Hu, Leif Hendricks, James E. Evans, Ashish Bhattarai, Wayne P. Hess, Patrick Z. El-Khoury
    更新日期:2017-09-04
  • Simultaneous effects of pressure and temperature on the optical transition energies in a Ga0.7In0.3N/GaN quantum ring
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-30
    K. Jaya Bala, A. John Peter, Chang Woo Lee

    Simultaneous effects of pressure and temperature on electronic and optical properties are studied in a Ga0.7In0.3N/GaN quantum ring using variational formulism. The changes in exciton binding energy due to the applications of hydrostatic pressure and temperature are obtained taking into account the geometrical confinement. The transition energies of interband and intersubband as a function of hydrostatic pressure, at a constant temperature, are obtained. The oscillator strength due to interband and intersubband optical transitions with the combined effects of hydrostatic pressure and temperature is found. The pressure and temperature induced absorption coefficients as a function of photon energy are investigated in a Ga0.7In0.3N/GaN quantum ring. The results show that the application of pressure leads to blue shift of the resonant peaks of the optical transition whereas the effect of temperature suffers red shift of the resonant peaks.

    更新日期:2017-08-31
  • Investigation on electronic properties of functionalized arsenene nanoribbon and nanotubes: a first-principles study
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-24
    V. Nagarajan, R. Chandiramouli
    更新日期:2017-08-24
  • Adsorption of O, O2 and CO on iridium clusters and the investigations of their stability
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-22
    Muna Tayyem, Bothina Hamad, Beate Paulus

    Density functional theory calculations were performed to study the stability of Irn clusters as well as the adsorption of O, O2 and CO adsorbates on selected structures. The clusters form three dimensional structures for n > 4. Larger clusters of n >13 exhibit simple cubic structures up to n around 32, beyond which fcc structures become more favorable. The binding energy is found to increase as a function of cluster size to approach bulk cohesive energy asymptotically. The total magnetic moment is found to decrease as a function of the cluster size approaching the bulk nonmagnetic ground state. The top adsorption site is the most site of O, O2 and CO on small clusters, unlike Ir64 that exhibits hollow, bridge and top sites, respectively. The vibrational frequencies of CO (O2) on Ir2 and Ir4 are found to be less than those of free molecules of 2102.82 (1562.08) cm-1.

    更新日期:2017-08-22
  • Two types of coherence resonance in an intracellular calcium oscillation system
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-12
    Juan Ma, Qingyu Gao
    更新日期:2017-08-17
  • Molecular dynamics of supercooled ionic liquids studied by light scattering and dielectric spectroscopy
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-07
    Florian Pabst, Jan Gabriel, Peter Weigl, Thomas Blochowicz

    We investigate molecular dynamics of two supercooled room temperature ionic liquids (RTILs) above of their glass transition temperature by means of dynamic light scattering and broadband dielectric spectroscopy from nanoseconds up to ≈105 ≈ 10 5 seconds. We show that a direct comparison of the raw data of these two techniques allows us to identify the reorientation of ions in the dielectric data, giving experimental evidence to a very recently proposed model of Gainaru et. al, [1] stating that the conductivity process in ionic liquids takes place through a reorientational step of ions escaping their cage formed by surrounding counterions. Within this approach we can also understand the apparent decoupling of time constants from dielectric spectroscopy and light scattering, often found in ionic liquids, in a very natural way. Furthermore, as a consequence of knowing the reorientational part of the dielectric spectrum, we are able to show that two more processes contribute to these spectra, which are due to electrode polarization effects. The relative position of all three contributions vary among the systems and may overshadow each other, thus complicating the data analysis and favor misinterpretations.

    更新日期:2017-08-07
  • Shell effect on the electron and hole reorganization energy of core-shell II-VI nanoclusters
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-05
    Xianhui Cui, Xinqin Wang, Fang Yang, Yingqi Cui, Mingli Yang
    更新日期:2017-08-06
  • About mobility thickness dependence in molecularly doped polymers
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-04
    A.P. Tyutnev, D.S. Weiss, V.S. Saenko, E.D. Pozhidaev
    更新日期:2017-08-05
  • 更新日期:2017-08-04
  • Vibrational Spectroscopy Modeling of a Drug in Molecular Solvents and Enzymes
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-04
    Christian J. Devereux, Kristen D. Fulfer, Xiaoliu Zhang, Daniel G. Kuroda
    更新日期:2017-08-04
  • Analysis of the non-Markovianity for electron transfer reactions in an oligothiophene-fullerene heterojunction
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-03
    E. Mangaud, C. Meier, M. Desouter-Lecomte

    The non-Markovianity of the electron transfer in an oligothiophene-fullerene heterojunction described by a spin-boson model is analyzed using the time dependent decoherence canonical rates and the volume of accessible states in the Bloch sphere. The dynamical map of the reduced electronic system is computed by the hierarchical equations of motion methodology (HEOM) providing an exact dynamics. Transitory witness of non-Markovianity is linked to the bath dynamics analyzed from the HEOM auxiliary matrices. The signature of the collective bath mode detected from HEOM in each electronic state is compared with predictions of the effective mode extracted from the spectral density. We show that including this main reaction coordinate in a one-dimensional vibronic system coupled to a residual bath satisfactorily describes the electron transfer by a simple Markovian Redfield equation. Non-Markovianity is computed for three inter fragment distances and compared with a priori criterion based on the system and bath characteristic timescales.

    更新日期:2017-08-03
  • A statistical mechanics investigation about general aspects of wetting transition occurring in nonpolar neutral molecule system with a smooth solid wall
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-01
    Shiqi Zhou

    Classical density functional theory is used to study the general aspects of wetting phenomena occurring in nonpolar neutral molecule system near a flat solid wall. Current cognitions of the wetting behavior are looked at, validated, corrected and extended. Several new observations are made: (i) the present theoretical calculations suggest that over a broad range of the surface potential parameters the pre-wetting transition temperature interval significantly reduces with the wetting temperature, and at the same time a continuous and monotonous increase of the wetting temperature is induced by decreasing the surface potential range and/or relative strength of surface atom versus fluid atom interaction. (ii) There exist lower limit values of both the surface potential range and the relative strength, below which the wetting transition is impossible. (iv) The present theoretical calculations confirm an experimentally found no adsorption occurring in weak surface potential substrates all the way to the relevant critical temperature by showing the impossibility of wetting at bulk critical temperature and its surroundings; moreover, the calculations extend the experimental observation to a wider parameter domain by indicating that the impossibility is not only unique feature of the weak surface potential substrates, but also applies to all situations of the surface potential range and relative strength. (v) With progressive increase of the relative strength and/or progressive decrease of the temperature, the interfacial phase behavior becomes increasingly complex: the (pre-)wetting transition and layering transition (which can be thermodynamically stable, metastable or even situated at supersaturated vapor phase) are intertwined closely; this challenges the popular knowledge that there is no (pre-)wetting for strong substrates for which the pre-wetting is replaced by the layering transitions.

    更新日期:2017-08-02
  • Irreversible thermodynamic analysis and application for molecular heat engines
    Chem. Phys. (IF 1.767) Pub Date : 2017-08-01
    Umberto Lucia, Emin Açıkkalp

    Is there a link between the macroscopic approach to irreversibility and microscopic behaviour of the systems? Consumption of free energy keeps the system away from a stable equilibrium. Entropy generation results from the redistribution of energy, momentum, mass and charge. This concept represents the essence of the thermodynamic approach to irreversibility. Irreversibility is the result of the interaction between systems and their environment. The aim of this paper is to determine lost works in a molecular engine and compare results with macro (classical) heat engines. Firstly, irreversible thermodynamics are reviewed for macro and molecular cycles. Secondly, irreversible thermodynamics approaches are applied for a quantum heat engine with -1/2 spin system. Finally, lost works are determined for considered system and results show that macro and molecular heat engines obey same limitations. Moreover, a quantum thermodynamic approach is suggested in order to explain the results previously obtained from an atomic viewpoint.

    更新日期:2017-08-02
  • AIMS Simulation Study of Ultrafast Electronically Nonadiabatic Chemistry of Methyl Azide and UV-VIS Spectroscopic Study of Azido-Based Energetic Plasticizer bis(1,3-diazido prop-2-yl)malonate
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-29
    Jayanta Ghosh, Shaibal Banerjee, Atanu Bhattacharya

    To gain insight into the ultrafast electronically nonadiabatic chemistry of azido-based energetic plasticizer, we have explored the nonadiabatic chemical dynamics of an azido-based model analog molecule, methyl azide (MAz), using ab initio multiple spawning (AIMS) simulation and electronic structure theory calculations. Molecular nitrogen (N2) is predicted to be the initial product of MAz following its electronic excitation to the S1 electronically excited state. AIMS-based simulation reveals that electronically excited azido-based molecules undergo extremely fast (approximately in 40 femtoseconds) relaxation to the ground state via the (S1/S0)CI conical intersection. Furthermore, this relaxation process involves the N-N bond elongation along with the bending of N3 moiety. This is the first report on the electronically non-adiabatic chemical dynamics (in ultrafast time domain) of methyl azide. Finally, using ultraviolet-visible (UV-VIS) spectroscopy, we comment on the electronically nonadiabatic chemistry of azido-based energetic plasticizer, bis(1,3-diazido prop-2-yl)malonate.

    更新日期:2017-07-30
  • Theoretical Prediction of Noble Gas Inserted Halocarbenes: FNgCX (Ng = Kr, and Xe; X = F, Cl, Br, and I)
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-20
    Pragya Chopra, Ayan Ghosh, Banasri Roy, Tapan K. Ghanty
    更新日期:2017-07-21
  • Electronic structures and population dynamics of excited states of xanthione and its derivatives
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-19
    Roman G. Fedunov, Marina V. Rogozina, Svetlana S Khokhlova, Anatoly I. Ivanov, Sergei A. Tikhomirov, Stanislav L. Bondarev, Tamara F. Raichenok, Oleg V. Buganov, Vyacheslav K. Olkhovik, Dmitrii A. Vasilevskii
    更新日期:2017-07-20
  • Plasmon Enhanced Heterogeneous Electron Transfer with Continuous Band Energy Model
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-17
    Dandan Zhao, Lu Niu, Luxia Wang

    Photoinduced charge injection from a perylene dye molecule into the conduction band of a TiO2 system decorated by a metal nanoparticles (MNP) is studied theoretically. Utilizing the density matrix theory the charge transfer dynamics is analyzed. The continuous behavior of the TiO2 conduction band is accounted for by a Legendre polynomials expansion. The simulations consider optical excitation of the dye molecule coupled to the MNP and the subsequent electron injection into the TiO2 semiconductor. Due to the energy transfer coupling between the molecule and the MNP optical excitation and subsequent charge injection into semiconductor is strongly enhanced. The respective enhancement factor can reach values larger than 103. Effects of pulse duration, coupling strength and energetic resonances are also analyzed. The whole approach offers an efficient way to increase charge injection in dye-sensitized solar cells.

    更新日期:2017-07-19
  • Coalesced nanomorphology, in situ, and ex situ applications of self assembled Gallium droplets grown by metal organic chemical vapor deposition
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-17
    J. Lohani, R.K. Bag, M.V.G. Padmavati, S. Sapra, R. Tyagi
    更新日期:2017-07-19
  • Quantum optimal control of the isotope-selective rovibrational excitation of diatomic molecules
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-15
    Yuzuru Kurosaki, Keiichi Yokoyama

    We carry out optimal control theory calculations for isotope-selective pure rotational and vibrational-rotational excitations of diatomic molecules. The fifty-fifty mixture of diatomic isotopologues, 7Li37Cl and 7Li35Cl, is considered and the molecules are irradiated with a control pulse. In the wave packet propagation we employ the method quantum mechanically rigorous for the two-dimensional system including both the radial and angular motions. We investigate quantum controls of the isotope-selective pure rotational excitation for two total times 1280000 and 2560000 a.u. (31.0 and 61.9 ps) and the vibrational-rotational excitation for three total times, 640000, 1280000, and 2560000 a.u. (15.5, 31.0, and 61.9 ps) The initial state is set to that both the isotopologues are in the ground vibrational and rotational levels, v = 0 and J = 0. The target state for pure rotational excitation is set to 7Li37Cl (v = 0, J = 1) and 7Li35Cl (v = 0, J = 0); that for vibrational-rotational excitation is set to 7Li37Cl (v = 1, J = 1) and 7Li35Cl (v = 0, J = 0). The obtained final yields are quite high and those for the longest total time are calculated to be nearly 1.0. When total time is 1280000 a.u., the final yields for the pure rotational excitation are slightly smaller than those for the vibrational-rotational excitation. This is because the isotope shift (difference in transition energy between the two isotopologues) for the pure rotational transition between low-lying levels is much smaller than that for the vibrational-rotational transition. We thus theoretically succeed in controlling the isotope-selective excitations of diatomic molecules using the method including both radial and angular motions quantum mechanically.

    更新日期:2017-07-16
  • A Test of the Significance of Intermolecular Vibrational Coupling in Isotopic Fractionation
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-15
    Michael F. Herman, Robert P. Currier, Travis B. Peery, Samuel M. Clegg

    Intermolecular coupling of dipole moments is studied for a model system consisting of two diatomic molecules (AB monomers) arranged co-linearly and which can form non-covalently bound dimers. The dipolar coupling is a function of the bond length in each molecule as well as of the distance between the centers-of-mass of the two molecules. The calculations show that intermolecular coupling of the vibrations results in an isotope-dependent modification of the AB-AB intermolecular potential. This in turn alters the energies of the low-lying bound states of the dimers, producing isotope-dependent changes in the AB-AB dimer partition function. Explicit inclusion of intermolecular vibrational coupling then changes the predicted gas-dimer isotopic fractionation. In addition, a mass dependence in the intermolecular potential can also result in changes in the number of bound dimer states in an equilibrium mixture. This in turn leads to a significant dimer population shift in the model monomer-dimer equilibrium system considered here. The results suggest that intermolecular coupling terms should be considered when probing the origins of isotopic fractionation.

    更新日期:2017-07-16
  • π π -stacking interactions in YFP, quantum mechanics and force field evaluations in the S0 and S1 states
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-15
    Karim Elhadj Merabti, Sihem Azizi, Jacqueline Ridard, Bernard Lévy, Isabelle Demachy

    We study the π π -stacking interaction between the chromophore and Tyr203 in the Yellow Fluorescent Protein (YFP) in order to (i) evaluate the contribution of the internal interaction energy of the isolated Chromophore-Tyrosine complex (Eint E int ) to the 26 nm red shift observed from GFP to YFP, (ii) compare the effects of Eint E int and of the proteic environment. To that end, we perform quantum mechanical and force field (ff) calculations of the isolated complex in S0 and S1 states on a large sample of geometries, together with molecular dynamics simulations and potential of mean force analysis. The calculated absorption wavelengths are found red shifted with respect to the isolated chromophore by 12-19 nm, that represents a large part of the GFP-YFP shift. We find that the effect of the protein is determinant on the dynamics of the complex while the error that results from using a classicalff is of limited effect.

    更新日期:2017-07-15
  • 更新日期:2017-07-11
  • An exactly solvable model of polymerization
    Chem. Phys. (IF 1.767) Pub Date : 2017-07-03
    A.A. Lushnikov

    This paper considers the evolution of a polydisperse polymerizing system comprising g1,g2… g 1 , g 2 … – mers carrying ϕ1,ϕ2… ϕ 1 , ϕ 2 … functional groups reacting with one another and binding the g–mers together. In addition, the g–mers are assumed to be added at random by one at a time with a known rate depending on their mass g   and functionality ϕ ϕ . Assuming that the rate of binding of two g–mers is proportional to the product of the numbers of nonreacted functional groups the kinetic equation for the distribution of clusters (g–mers) over their mass and functionalities is formulated and then solved by applying the generating function method. In contrast to existing approaches this kinetic equation operates with the efficiencies proportional to the product of the numbers of active functional groups in the clusters rather than to the product of their masses. The evolution process is shown to reveal a phase transition: the emergence of a giant linked cluster (the gel) whose mass is comparable to the total mass of the whole polymerizing system. The time dependence of the moments of the distribution of linked components over their masses and functionalities is investigated. The polymerization process terminates by forming a residual spectrum of sol particles in addition to the gel.

    更新日期:2017-07-03
  • Temperature Dependence of the Spin Relaxation Time of Fe3O4 and Hemozoin Superparamagnetic Nanocrystals
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-30
    I. Khmelinskii, V. Makarov
    更新日期:2017-06-30
  • Van der Waals Potential and Vibrational Energy Levels of the Ground State Radon Dimer
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-30
    Xiaowei Sheng, Shifeng Qian, Fengfei Hu

    In the present paper, the ground state van der Waals potential of the Radon dimer is described by the Tang-Toennies potential model, which requires five essential parameters. Among them, the two dispersion coefficients C6 C 6 and C8 C 8 are estimated from the well determined dispersion coefficients C6 C 6 and C8 C 8 of Xe2. C10 C 10 is estimated by using the approximation equation that View the MathML source C 6 C 10 / C 8 2 has an average value of 1.221 for all the rare gas dimers. With these estimated dispersion coefficients and the well determined well depth De D e and Re R e the Born-Mayer parameters A A and b b are derived. Then the vibrational energy levels of the ground state radon dimer are calculated. 40 vibrational energy levels are observed in the ground state of Rn2 dimer. The last vibrational energy level is bound by only 0.0012 cm-1.

    更新日期:2017-06-30
  • Transport coefficients and validity of the Stokes-Einstein relation in metallic melts: from excess entropy scaling laws
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-29
    Ruchi Shrivastava, Raj Kumar Mishra
    更新日期:2017-06-30
  • Another Look at Structure of Gold Clusters Aun from Perspective of Phenomenological Shell Model
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-29
    Pham Vu Nhat, Nguyen Thanh Si, Jerzy Leszczynski, Minh Tho Nguyen
    更新日期:2017-06-29
  • Natural optical activity of f-f transitions in ErAl3(BO3)4 single crystal
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-27
    A.V. Malakhovskii, V.V. Sokolov, I.A. Gudim
    更新日期:2017-06-28
  • Characteristics of methylammonium ion (CH3NH3+) in aqueous electrolyte solution: An ONIOM-XS MD simulation study
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-27
    Prangthong Chaiyasit, Anan Tongraar, Teerakiat Kerdcharoen
    更新日期:2017-06-28
  • Ab initio quantum direct dynamics simulations of ultrafast photochemistry with Multiconfigurational Ehrenfest approach
    Chem. Phys. (IF 1.767) Pub Date : 2017-04-14
    Dmitry Makhov, Christopher Symonds, Sebastian Fernandez-Alberti, Dmitrii Shalashilin

    The Multiconfigurational Ehrenfest (MCE) method is a quantum dynamics technique which allows treatment of a large number of quantum nuclear degrees of freedom. This paper presents a review of MCE and its recent applications, providing a summary of the formalisms, including its ab initio direct dynamics versions and also giving a summary of recent results. Firstly, we describe the Multiconfigurational Ehrenfest version 2 (MCEv2) method and its applicability to direct dynamics and report new calculations which show that the approach converges to the exact result in model systems with tens of degrees of freedom. Secondly, we review previous “on the fly” ab initio Multiple Cloning (AIMC-MCE) MCE dynamics results obtained for systems of a similar size, in which the calculations treat every electron and every nucleus of a polyatomic molecule on a fully quantum basis. We also review the Time Dependent Diabatic Basis (TDDB) version of the technique and give an example of its application. We summarise the details of the sampling techniques and interpolations used for calculation of the matrix elements, which make our approach efficient. Future directions of work are outlined.

    更新日期:2017-06-27
  • A coarse-grained method to predict the open-to-closed behavior of glutamine binding protein
    Chem. Phys. (IF 1.767) Pub Date : 2017-05-27
    Dashuai Lv, Weikang Gong, Yue Zhang, Yang Liu, Chunhua Li

    The Glutamine-Binding Protein (GlnBP) of Escherichia coli is responsible for the first step in the active transport of glutamine across the cytoplasmic membrane. In present work, we explored the allosteric pathway of GlnBP from the open to closed states during the substrate binding process with the adaptive anisotropic network model (aANM). The results show that the allosteric transition proceeds in a coupled way and is more likely to be driven by the movement of hinge regions. The large-scale hinge-bending motion between the large and small domains occurs, accompanied by an interdomain twisting motion which proceeds mainly in the middle stage. The cooperative motion between the dominant hinge-bending motion and the twisting motion exerts a crucial role in the open-closed motions of GlnBP. These results are in close agreement with previous experimental and theoretical data, implying that the topology structure plays a crucial role in the allosteric transition process of GlnBP.

    更新日期:2017-06-27
  • Wavelength dependence of high-harmonic yield in stretched molecules
    Chem. Phys. (IF 1.767) Pub Date : 2017-06-11
    Shengjun Yue, Hongchuan Du, Hongmei Wu, Jinbin Li, Bitao Hu
    更新日期:2017-06-27
  • 更新日期:2017-06-27
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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