First-principles nonlocal-pseudopotential approach in the density-functional formalism. II. Application to electronic and structural properties of solids

Abstract

We apply our previously developed first-principles nonlocal pseudopotentials (obtained for all atoms of rows 1-5 in the Periodic Table) to study self-consistently the electronic structure of Si and Ge and the transition metals Mo and W. For Si and Ge we find that the first-principles pseudopotentials yield valenceband states in good agreement with the empirically adjusted pseudopotential and photoemission data, whereas the low conduction-band states appear to be consistently lower in energy due apparently to incomplete cancellation of the self-interaction effects. The calculated x-ray scattering factors (obtained by core orthogonalization of the pseudo-wave-functions) are in excellent agreement with experiment. The self-consistent valence charge density shows a distinct elongation of the covalent bond along the internuclear axis, in good agreement with the experimentally synthesized density. The systematic deviations of the empirical pseudopotential results from the present are discussed in terms of the underlying differences in the potentials in the high-momentum regions. Using a mixed Gaussian-plane-wave representation, we calculated the self-consistent band structures of Mo and W, and compared them with the available augmented-plane-wave results. We find good agreement in the internal structure of the $d$ bands, however, the present nonmuffin-tin self-consistent calculation yields substantially different $s\ensuremath{-}d$ and $p\ensuremath{-}d$ splittings. The bonding characteristics and Fermi surfaces in these materials are discussed. Finally, we show that these first-principles potentials provide a topological separation of both the octet ${A}^{N}{B}^{8\ensuremath{-}N}$ and the suboctet ${A}^{N}{B}^{P\ensuremath{-}N}$ ($3\ensuremath{\le}P\ensuremath{\le}6$) crystal structures. It is concluded that the presently developed pseudopotentials can be successfully used for studying both the electronic structure of wide range of materials and structural properties, without resorting to empirical parametrization.