Chemical potentialμ_ehand radiative lifetimeτ_radbehaviourvs.carrier densitynin FASnI₃. They change dramatically with hole doping concentration, inducing large Burstein–Moss shift

Relaxations at nonpolar surfaces of semiconductor III-V compounds result from a competition between dehybridization and charge transfer. First-principles calculations for the (110) and (10$1¯$0) faces of zinc-blende and wurtzite AlN, GaN, and InN reveal an anomalous behavior as compared with ordinary III-V semiconductors. Additional calculations for GaAs and ZnO suggest close analogies with the latter. We interpret our results in terms of the larger ionicity (charge asymmetry) and bonding strength (cohesive energy) in the nitrides with respect to other III-V compounds, both essentially due to the strong valence potential and absence of p core states in the lighter anion. The same interpretation applies to Zn II-VI compounds.

We present an on-line database of all-atom force-field parameters and molecular properties of compounds with antimicrobial activity (mostly antibiotics and some beta-lactamase inhibitors). For each compound, we provide the General Amber Force Field parameters for the major species at physiological pH, together with an analysis of properties of interest as extracted from µs-long molecular dynamics simulations in explicit water solution. The properties include number and population of structural clusters, molecular flexibility, hydrophobic and hydrophilic molecular surfaces, the statistics of intraand inter-molecular H-bonds, as well as structural and dynamical properties of solvent molecules within first and second solvation shells. In addition, the database contains several key molecular parameters, such as energy of the frontier molecular orbitals, vibrational properties, rotational constants, atomic partial charges and electric dipole moment, computed by Density Functional Theory. The present database (to our knowledge the first extensive one including dynamical properties) is part of a wider project aiming to build-up a database containing structural, physico-chemical and dynamical properties of medicinal compounds using different force-field parameters with increasing level of complexity and reliability. The database is freely accessible at http://www.dsf.unica.it/translocation/db/.

A method is presented for the generation of valence-only local Hamiltonians, or pseudo-Hamiltonians, within the framework of the local-density-functional theory. Extensive transferability tests for atoms and crystals show that the performance of pseudo-Hamiltonians in density-functional-theory calculations matches the standards of other state-of-the-art methods. These pseudo-Hamiltonians represent a useful tool for quantum Monte Carlo simulations of many sp-bonded valence-only systems.

We evaluate theoretically the thermoelectric efficiency of the layered perovskite ${\mathrm{Sr}}_2{\mathrm{Nb}}_2{\mathrm{O}}_7$ via calculations of the electronic structure and transport coefficients within density-functional theory and Bloch-Boltzmann relaxation-time transport theory. The predicted figure-of-merit tensor $ZT$, computed with energy-, chemical potential–, and temperature-dependent relaxation times, has one component increasing monotonically from around 0.4 at room temperature to 2.4 at 1250 K at an optimal carrier density of around $2\times {10}^{20}{\mathrm{cm}}^{-3}$, while the other components are small. The Seebeck coefficient is about 250 to 300 $\mu \mathrm{V}$/K at optimal doping and reaches 800 $\mu \mathrm{V}$/K at lower doping. We provide a python code implementing various approximations to the energy-dependent relaxation-time transport, which can be used to address different systems with an appropriate choice of material parameters.