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 localized orthogonal orbitals (Wannier functions) of a crystalline insulator 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 pseudo or model potentials. Quantities such as total energy, x-ray structure factors and Compton profiles obtained using the localized Hartree-Fock orbitals are shown to be in excellent agreement with the corresponding quantities calculated using the conventional Bloch-orbital based Hartree-Fock approach. Localization characteristics of these orbitals are also discussed in detail.