OBTAINING WANNIER FUNCTIONS OF A CRYSTALLINE INSULATOR WITHIN A HARTREE-FOCK APPROACH - APPLICATIONS TO LIF AND LICL

An ab initio Hartree-Fock approach aimed at directly obtaining the loc alized orthogonal orbitals (Wannier functions) of a crystalline insula tor is described in detail. The method is used to perform all-electron calculations on the ground states of crystalline lithium fluoride and lithium chloride, without the use of any pseudopotentials or model po tentials. Quantities such as total-energy, x-ray structure factors, an d Compton profiles obtained using the localized Hartree-Fock orbitals are shown to be in excellent agreement with the corresponding quantiti es calculated using the conventional Bloch-orbital-based Hartree-Fock approach. Localization characteristics of these orbitals are also disc ussed in detail.