Calculation of the Matrix Elements of the Long-Range Coulomb Interaction Comparison of the GTO and STO Approaches

A method for calculating the matrix elements of the long-range Coulomb interaction is proposed. The method is based on the Slater-type orbitals (STO) of ions forming an infinite crystal lattice. One-center matrix elements of the Coulomb interaction of an electron of a selected ion with a crystal lattice taken in the ionic approximation are considered. All obtained expressions are absolutely and rapidly convergent series in the space of reciprocal lattice vectors. The STO method is compared with the Gaussian-type orditals method and is illustrated by examples.