Band-gap problem is the fundamental issue which underlies the predictive inaccuracy in a number of applications, e.g., the determination of defect energy levels in solid. In this talk, we will first show that defect energy levels can be obtained reliably through hybrid-functional and many-body $GW$ calculations provided that the band gaps are well accounted for. We will then outline recent...
Approximate density functionals produce total energies that do not exhibit the expected piecewise-linear behavior as a function of the particle number, leading to a discrepancy between total and partial electron removal/addition energies and poor predictive capabilities of ionization potentials. Koopmans-compliant functional enforce a generalized criterion of piecewise linearity in the energy...
Copper vanadates have recently shown promise as photoanodes for water-splitting photoelectrochemical cells. However, studies revealed that their performance is severely limited. We study, both experimentally and computationally, the electronic structure, excitonic effects and optical properties of β-Cu2V2O7. To achieve an accurate description of the properties of this complex oxide, we perform...
We present a theoretical formulation for studying the pH-dependent interfacial coverage of semiconductor-water interfaces through ab initio electronic-structure calculations, molecular dynamics simulations, and the thermodynamic integration method. The proposed method is applied to study the BiVO4(010)-water interface and yields a pH at the point of zero charge in excellent...
An accurate modeling of transition-metal compounds is central to many scientific problems and technological applications including battery materials, photovoltaics, multiferroics, superconductors.
Unfortunately, approximate DFT functionals do not capture electronic localization in low-dispersion states (e.g., d or f) and misrepresent important properties of these systems.
This work shows how...
DFT+U+V is a simple and powerful tool to model systems containing partially-filled manifolds of localized states. However, the Hubbard parameters are often treated semi-empirically, which is a somewhat unsatisfactory approach. Conceptual and practical methods to determine e.g. the Hubbard U parameter from first principles have nevertheless been introduced long ago, based either on the...
Enforcing the generalized Koopmans’ condition, we construct hybrid density functionals which give band gaps of solids as accurate as state-of-the-art GW calculations and are also capable to correctly describe polaronic distortions. Based on this nonempirical formulation, we address the energetics of native point defects and impurities in GaN. Our results show an amphoteric nature of Mg...
see attached
We investigate the stability of hole polarons at the rutile surface induced by electronegative adsorbates in the intermediate steps of the oxygen evolution reaction through hybrid density functional calculations. Applying the computational hydrogen electrode method, we find that hole polarons reduce the overpotential of the reaction determining step leading to good agreement with experiment....
High entropy alloys (HEAs) are random alloys with 5 or more components, of near-equi-composition. HEAs exhibit excellent mechanical properties, including high strength, ductility, and fracture toughness. Guiding the design of new HEAs across the composition space requires an ability to compute necessary underlying material parameters accurately. Here, we propose a methodology to compute, via...
We trained a deep neural network potential [1] based on a set of data generated by well-tempered metadynamics [2] simulations that use a classical potential.
We employed the SCAN exchange-correlation functional [3] and converged the calculations with respect to BZ sampling.
The resulting potential is used to study the nucleation and liquid state properties of silicon, on timescales and system...
GaAs nanowires grown with the vapor-liquid-solid method exhibit complex behavior at the solid-liquid interface, with Wurtzite and Zincblende competing for stability on the As-terminated surface.
Atomistic models can help understanding this phenomenon, but the necessary length and size scales are beyond those accessible by ab initio molecular dynamics (AIMD).
We tested the combination of AIMD...
