Beryllium-Hydrogen Ultrathin Films. 1. Metallic Behavior of the BeH2 Monolayer.

摘要

Equilibrium lattice parameters, total energies, in-plane energy second derivative, and Kohn-Sham energy bands for the BeH2 1-layer are determined by all-electron, full potential, local-density-functional calculations. The BeH2 layer is predicted to be metallic, contrast with a previous Hartee-Fock calculation, this disparity is traced to basis-set restrictions in the Hartee-Fock calculation that drive the highly localized Be surface state into the conduction band. The minimum-energy lattice constant a (i.e., the square edge that is twice the Be-H distance) for the BeH2 1-layer is 5.51 a.u. The calculated H-H distance is 3.90 a.u., lower than Switendick's empirical criterion (3.97 a.u.) for stable metal hydrides but still well above the 3.40 a.u. involved in Overhauser's conjecture about superconductivity in LiBeH3. Reprints. (jes)