Improved hybrid functional for solids: the HSEsol functional.

We introduce the hybrid functional HSEsol. It is based on PBEsol, a revised Perdew-Burke-Ernzerhof functional, designed to yield accurate equilibrium properties for solids and their surfaces. We present lattice constants, bulk moduli, atomization energies, heats of formation, and band gaps for extended systems, as well as atomization energies for the molecular G2-1 test set. Compared to HSE, significant improvements are found for lattice constants and atomization energies of solids, but atomization energies of molecules are slightly worse than for HSE. Additionally, we present zero-point anharmonic expansion corrections to the lattice constants and bulk moduli, evaluated from ab initio phonon calculations.

Accurate bulk properties from approximate many-body techniques.

For ab initio electronic structure calculations, the random-phase approximation to the correlation energy is supposed to be a suitable complement to the exact exchange energy. We show that lattice constants, atomization energies of solids, and adsorption energies on metal surfaces evaluated using this approximation are in very good agreement with experiment. Since the method is fairly efficient and handles ionic, metallic, and van der Waals bonded systems equally well, it is a very promising choice to improve upon density functional theory calculations, without resorting to more demanding diffusion Monte Carlo or quantum chemical methods.

A first-principles study of bulk oxide formation on Pd(100).

The catalytic oxidation activity of palladium is influenced by the oxidation state of the metal. Under technologically relevant conditions, bulk and surface oxides may form and decompose. By employing first-principles calculations based on density functional theory, we have investigated the transition from the surface oxide to the bulk oxide on Pd(100). We show that the most stable orientation of the oxide film is PdO(101)@Pd(100) at any film thickness. The monolayer has unique electronic, chemical, and thermodynamic properties in comparison to thicker oxide films. In particular, carbon monoxide adsorbs by approximately 0.3 eV more strongly on thicker oxides than on the surface oxide, a fact that should influence the catalytical activity. Finally, we show that a simple model employing density functional theory energies predicts a Stranski-Krastanov growth mode for the oxide film, with a critical thickness of 1 ML. Our results give a framework for the interpretation of experiments of Pd oxide growth.

Making the random phase approximation to electronic correlation accurate.

We show that the inclusion of second-order screened exchange to the random phase approximation allows for an accurate description of electronic correlation in atoms and solids clearly surpassing the random phase approximation, but not yet approaching chemical accuracy. From a fundamental point of view, the method is self-correlation free for one-electron systems. From a practical point of view, the approach yields correlation energies for atoms, as well as for the jellium electron gas within a few kcal/mol of exact values, atomization energies within typically 2-3 kcal/mol of experiment, and excellent lattice constants for ionic and covalently bonded solids (0.2% error). The computational complexity is only O(N(5)), comparable to canonical second-order Møller-Plesset perturbation theory, which should allow for routine calculations on many systems.