Application of the discrete variational method to the electronic structure of LiF

The discrete variational method, which has been successfully applied previously to several covalent crystals, has been used to calculate the energy bands and charge density of the ionic crystal LiF, using various crystal potential models. The great sensitivity of the energy bands to the atomic configuration used to construct the potential and to the scaling of the statistical exchange is explained in terms of differences in the spatial properties of the crystal wave functions. The excited bands are found to be characterized by diffuse orbitals which are converged by using a mixed basis of Bloch atomic-like functions and symmetrized plane waves. Basis convergence problems posed by ionic systems for linear variational techniques are discussed in the conclusion.