On the core expansion of metallic beryllium

Core contributions to charge densities, X-ray structure factors, Compton profiles and kinetic energies of metallic beryllium have been calculated using an ab initio Hartree-Fock self-consistent-field method, and compared with the corresponding atomic quantities. As previously suggested by some authors, the metallic core is slightly expanded with respect to that in the atom, the expansion affecting the total calculated quantities by less than 1%. When compared with the binding energy (3.3 eV/atom) the difference in the core contributions to the kinetic energy (1.5 eV) is not negligible, and arises from a large momentum interval (0 < q < 10 a.u.). (author)