Calculation of the self-consistent-field electronic wave functions of crystals using Wannier-type functions: The case of LiH

In the present paper, we propose a method for the calculation of self-consistent field (SCF) wave functions of crystals. This method is based on a partial transfer of Wannier-type functions from small model systems into the crystal. Wannier-type functions are defined here by the conditions (i) that they are essentially localized on atoms and (ii) that they span a vector space containing exactly the occupied Bloch waves of the different bands of the crystal. Thus, these functions look very much like ordinary Wannier functions, but they are not necessarily orthogonal. An advantage of the partial transfer of Wannier-type functions is that it allows us to reduce the number of parameters to be used in the minimization of the energy per primitive cell of the crystal. The accuracy of the resulting SCF wave function has been checked by calculating a variety of observable quantities in the case of the LiH crystal. The agreement with existing experimental and/or theoretical values is very good in all cases.