We present here an analysis of the electronic structure of like-charge dimers that occur in a class of protic ionic materials based on the use of amino and phosphonic acids anions. Some of these materials have emerged in recent years as a possible replacement of first-generation ionic liquids because of their greater biocompatibility, biodegradability and the lower costs of their preparation. At the

The structural similarity between hexagonal boron nitride (h-BN) and graphene nanoribbons allows forming heterojunctions with small chain stress. The insulation nature of the former and the quasi-metallic property of the latter make them attractive for flat optoelectronics. Recently, shapes of graphene and h-BN domains were precisely controlled, creating sharp graphene/h-BN interfaces. Here, we investigated

High performance computing is a powerful tool to accelerate the Kohn–Sham density functional theory calculations on modern heterogeneous supercomputers. Here, we describe a massively parallel implementation of large-scale linear-response time-dependent density functional theory (LR-TDDFT) to calculate the excitation energies and wave functions of solids with plane-wave basis set. We adopt a two-level

The electronic structures of layered rare-earth tritelluride RTe3 (R = Pr, Er) charge density wave (CDW) compounds have been investigated by performing R 4d → 4f resonant photoemission spectroscopy (RPES) and angle-resolved photoemission spectroscopy (ARPES) measurements for high-quality single crystals. R 4d → 4f RPES measurements reveal that the R 4f states do not contribute directly to the CDW formation

The development of novel materials for vacuum electron sources in particle accelerators is an active field of research that can greatly benefit from the results of ab initio calculations for the characterization of the electronic structure of target systems. As state-of-the-art many-body perturbation theory calculations are too expensive for large-scale material screening, density functional theory

In this work, we investigated the electronic structure and the quantum capacitance of a set of functionalized MoS2 monolayers. The functionalizations have been done by using different ad-atom adsorption on MoS 2 monolayer. Density functional theory calculations are performed to obtain an accurate electronic structure of ad-atom doped MoS2 monolayer with a varying degree of doping concentration. Subsequently

We report computer assisted density functional theory computations of electronic states in carbide Co9S8/MoS2 interface model. The interface model was previously proposed using crystallographic information from experimental high-resolution TEM observations; and directly observed by in-situ heating to confirm carbon deposit occurs at the sulfur edge of Co9S8/MoS2 which creates a thin carbide layer.

Molecular exchange processes in organic heterostructures are often detrimental to the performance of nano-optoelectronic devices. Bilayers of vacuum sublimed organic semiconductors on inorganic substrates can serve as reductionist model for organic–organic interfaces and the coupling strength of the template layer on the substrate is a decisive factor for possible molecular exchange. We use density-functional

ABO3 perovskites host a huge range of symmetry lowering structural distortions, each of which can tune, or even switch on or off, different functional properties due to the strong coupling between the lattice, spin and charge degrees of freedom in these materials. The sheer number of different meta-stable structures present in perovskites creates a challenge for materials design via theory and simulation

Plane wave density functional theory codes generally assume periodicity in all three dimensions. This causes difficulties when studying charged systems, for instance energies per unit cell become infinite, and, even after being renormalised by the introduction of a uniform neutralising background, are very slow to converge with cell size. The periodicity introduces spurious electric fields which decay

Since the rising of graphene, boron nitride monolayers have been deeply studied due to their structural similarity with the former. A hexagonal graphene-like boron–carbon–nitrogen (h-BCN) monolayer was synthesized recently using bis-BN cyclohexane (B2N2C2H12) as a precursor molecule. Herein, we investigated the electronic and structural properties of this novel BCN material, in the presence of single-atom

Exciton band structures analysis provides a powerful tool to identify the exciton character of materials, from bulk to isolated systems, and goes beyond the mere analysis of the optical spectra. In this work, we focus on the exciton properties of molybdenum sisulfide (MoS2) by solving the ab initio many-body Bethe–Salpeter equation, as a function of momentum, to obtain the excitation spectra of both

Moir superlattices—periodic orbital overlaps and lattice-reconstruction between sites of high atomic registry in vertically-stacked 2D layered materials—are quantum-active interfaces where non-trivial quantum phases on novel phenomena can emerge from geometric arrangements of 2D materials, which are not intrinsic to the parent materials. Unexpected distortions in band-structure and topology lead to

A kernel polynomial method is developed to calculate the random phase approximation (RPA) correlation energy. In the method, the RPA correlation energy is formulated in terms of the matrix that is the product of the Coulomb potential and the density linear response functions. The integration over the matrix’s eigenvalues is calculated by expanding the density of states of the matrix in terms of the

Rechargeable batteries (Li-ion batteries and beyond) have received extensive attention as powerful boosters for the development of human society. The rapid progress achieved in this research area largely relies on the in-depth efforts on the improvement of battery electrode materials and decrease of the cost. However, the application of rechargeable batteries is still hindered by low energy density

Flexoelectricity is the polar response of an insulator to strain gradients such as bending. While the size dependence makes it weak in bulk systems in comparison to piezoelectricity, it can play a bigger role in nanoscale systems such as thin films and nanotubes (NTs). In this paper we demonstrate using first-principles calculations that the walls of carbon nanotubes (CNTs) and transition metal dichalcogenide

A relativistic transient absorption theory is derived, implemented and validated within the dipole approximation based on the time-dependent Dirac equation. In the non-relativistic limit, it is found that the absorption agrees with the well established non-relativistic theory based on the time-dependent Schrdringer equation. Time-dependent simulations have been performed using the Dirac equation and

Polynuclear transition metal complexes such as the P-cluster and the FeMo-cofactor of nitrogenase with eight transition metal centers represent a great challenge for current electronic structure methods. In this work, we initiated the use of comb tensor network states (CTNS), whose underlying topology has a one-dimensional backbone and several one-dimensional branches, as a many-body wavefunction ansatz

Amino acids are essential to all life. However, our understanding of some aspects of their intrinsic structure, molecular chemistry, and electronic structure is still limited. In particular the nature of amino acids in their crystalline form, often essential to biological and medical processes, faces a lack of knowledge both from experimental and theoretical approaches. An important experimental technique

A carbon quantum dot (CQD) sample series was synthesized from citric acid and varying concentrations of thiourea. The highest (sample 1) and lowest (sample 2) concentrations of thiourea exhibited unique visual effects and electronic structures. X-ray excited optical luminescence (XEOL) along with UV-visible spectroscopy provided unique insight into the absorption and emission mechanisms of samples

Transition metal nitrides possess important properties of interest such as superconductivity, high hardness, optical, electronic and magnetic among others which are relevant for technological applications. In this study, structural and magnetic properties of nitrides of iron and nickel have been investigated using generalized gradient approximation of Perdew–Burke–Ernzerhof revised for solids (GGA-PBEsol)

Electronic structures with the type-II band alignment usually exist only in heterostructures. Using the generalized Bloch theorem, we reveal that an effective type-II band alignment can be induced in the single crystalline TiO2 nanowires (NWs) by an axial twisting deformation. With this, we further reveal distinct responses of the the valence band (VB) states and the conduction band (CB) states in

Recently published density functional theory results using the PBE functional (Whaley-Baldwin and Needs 2020 New J. Phys. 22 023020) suggest that elemental sulfur does not adopt the simple-cubic (SC) phase at high pressures, in disagreement with previous works (Rudin and Liu 1999 Phys. Rev. Lett. 83 3049--52; Gavryushkin et al 2017 Phys. Status Solidi B 254 1600857). We carry out an extensive set of

The local atomic information about the interface between the 30 nm-thick Pt polycrystalline films and the solution with and without perfluorosulfonic acid polymers (Nafion) for the model cathode catalyst of fuel cell has been captured under electrochemical conditions using polarization-dependent total reflection fluorescence x-ray absorption near edge structure spectroscopy (PTRF–XANES). The results

Polycyclic aromatic systems are prevalent in chemistry and materials science because their thermodynamic stability, planarity, and tunable electronic properties make them uniquely suited for various uses. These properties are closely linked to the aromaticity of the systems. Therefore, characterizing the aromatic behavior is useful for designing new functional compounds and understanding their reactivity

This review outlines fundamental principles, instrumentation, and capabilities of angle-resolved photoemission spectroscopy (ARPES) and microscopy. We will present how high-resolution ARPES enables to investigate fine structures of electronic band dispersions, Fermi surfaces, gap structures, and many-body interactions, and how angle-resolved photoemission microscopy (spatially-resolved ARPES) utilizing

Yttrium iron garnet is a complex ferrimagnetic insulator with 20 magnon modes which is used extensively in fundamental experimental studies of magnetisation dynamics. As a transition metal oxide with moderate gap (2.8eV), yttrium iron garnet requires a careful treatment of electronic correlation. We have applied quasiparticle self-consistent GW to provide a fully ab initio description of the electronic

The large contact resistance is an insurmountable problem for the Schottky contact between the semiconducting two-dimensional channel material and the metal electrode. One solution to the Schottky contact issue is to decrease the contact resistance. Here, by using the first-principles calculations combined with the non-equilibrium Green’s function technique, we find that when monolayer arsenene is

X-ray emission spectroscopy (XES), as a complementary technique to x-ray absorption spectroscopy (XAS), is powerful in the analysis of the electronic structure of the materials by probing the occupied density of states with high energy resolution. Recently, an XES spectrometer optimized for the tender x-ray region (2–5 keV) was successfully installed into an inert atmosphere glovebox, and the entire

We introduce a design of a portable, multi-functional spectroscopic cell for in situ structural probe of materials using hard x-rays. This versatile reaction cell allows x-ray absorption fine structure (XAFS) and x-ray diffraction measurements in transmission mode on solids at a controlled temperature, pressure, and gas environment. A model heterogeneous catalysis system, co-aromatization of octane

We devise a mixing algorithm for full-potential (FP) all-electron calculations in the linearized augmented planewave (LAPW) method. Pulay’s direct inversion in the iterative subspace is complemented with the Kerker preconditioner and further improvements to achieve smooth convergence, avoiding charge sloshing and noise in the exchange–correlation potential. As the Kerker preconditioner was originally

A detailed understanding of interacting electrons in twisted bilayer graphene (tBLG) near the magic angle is required to gain insights into the physical origin of the observed broken symmetry phases. Here, we present extensive atomistic Hartree theory calculations of the electronic properties of tBLG in the (semi-)metallic phase as function of doping and twist angle. Specifically, we calculate quasiparticle

The electronic properties of hybrid organic–inorganic semiconductor interfaces depend strongly on the alignment of the electronic carrier levels in the organic/inorganic components. In the present work, we address this energy level alignment from first principles theory for two paradigmatic organic–inorganic semiconductor interfaces, the singlet fission materials tetracene and pentacene on H/Si(111)

The adsorption of molecules NH 3 , CH 4 , and H 2 O are studied on pristine and indium doped phosphorene (In@P). For adsorption, armchair (AC), zigzag, and isotropic/square supercells are used. We have calculated structural, adsorption energies and electronic properties using the first-principles method. The most stable configurations for adsorption on doped phosphorene are determined, and the adsorption

The perovskite oxides are known to be susceptible to structural distortions over a long wavelength when compared to their parent cubic structures. From an ab initio simulation perspective, this requires accurate calculations including many thousands of atoms; a task well beyond the remit of traditional plane wave-based density functional theory (DFT). We suggest that this void can be filled using the

Hafnium and zirconium mononitrides (HfN and ZrN) have been of interest for the hot carrier solar cell (HCSC) concept as a bulk absorber material and in thermoelectric power generation as a superlattice structure. Slowed hot carrier (HC) cooling is a fundamental requirement in an HCSC device because the carriers must be collected at high energy levels via energy selective contacts before they cool down

Structural, electronic and magnetic properties of four transition metal tri-chalcogenide monolayers—MnPS 3 , MnPSe 3 , FePS 3 and FePSe 3 —are studied using density functional theory. Lattice structures in good agreement with experiments are obtained. Electronic structure of the Mn compounds obtained using the PBE-GGA functional is in qualitative agreement with the experiments, apart from the well

Electron localisation descriptors, such as the electron localisation function (ELF) and localised orbital locator (LOL) provide a visual tool for interpreting the results of electronic structure calculations. The descriptors produce a quantum valence shell electron pair repulsion (VSEPR) representation, indicating the localisation of electron pairs into bonding pairs and lone pairs in single molecules

The major challenge of black phosphorus (BP) is its fast-oxidative degradation in air. Organic covalent chemical modification of BP flakes could suppress the chemical degradation. Here we focus on the effects of covalent chemical modification on the electronic structures of single layer BP. We employed the state-of-the-art first principles GW method, which is based on the many body green functions