Electronic-Structure Studies of Solids. II. "Exact" Hartree-Fock Calculations for Cubic Atomic-Hydrogen Crystals

A comprehensive description is given of rigorous Hartree-Fock calculations for cubic atomic-hydrogen crystals. All energy and overlap integrals are reduced to reciprocal-lattice sums. The exchange effects are treated exactly. The Bloch functions and Fermi surfaces are optimized. The near-Hartree-Fock results indicate essentially spherical Fermi surfaces and strong atomic-orbital behavior of the Bloch functions. The energetic effect associated with the atomlike inhomogeneities is about 15%. Good agreement is found between Kohn-Sham and Slater local-exchange potentials and exchange potentials deduced from our Hartree-Fock results.