Ab initio study of metallic beryllium

Hexagonal close-packed beryllium has been studied with an Hartree-Fock (HF) ab initio technique, with the use of an extended basis set. The conformational calculated minimum corresponds to a slightly expanded crystal lattice, and total energy is near to the estimated HF limit. The metallic character of the system, as illustrated by the shape of its Fermi surface, is in fair agreement with experiment. The general features of the electron distribution are satisfactorily reproduced both in direct and in reciprocal space, as results by comparison with experimental structure factors and Compton profiles. The present study gives evidence for the fundamental role of $p$-type functions in determining both the metallic character and the partly covalent bonds of beryllium.