Lithium crystal properties from high-quality Hartree-Fock wave functions

Properties derived from lithium b.c.c. crystal Hartree-Fock (HF) calculations, using LCAO-type Bloch functions and including 2s, 2p and 3d Slater-type basis orbitals, are presented. These include total energies, lattice parameters, band gaps, widths of the occupied part of valence band, bulk modulus and Fermi surface geometry. Energetic quantities are in qualitative agreement with our earlier work. Their disagreements with experiment again underscore some inadequacies of HF. The bulk modulus is overestimated by about 50%, which is typical for HF-based molecular force constants. The Fermi surface is calculated to have a maximum distortion (in the 〈110〉 direction) of about 3.5%. This is in agreement with the best experiments. The sensitivity of predicted distortions to Brillouin zone integration points is discussed.