A new computational approach to Slater’s SCF–Xα equation

A new computational scheme is presented for the performance of LCAO−MO calculations in the SCF−Xα model. The scheme is intended to be applicable for large systems and to be more accurate than the scattered−wave SCF−Xα method. The Xα potential is fitted by least−squares to a linear combination of Gaussians, and the approximated SCF−Xα equation is solved by the conventional Rayleigh−Ritz variational method. The muffin−tin approximation is avoided, and matrix elements are calculated analytically in contrast to the discrete variational scheme. Some illustrative results are given for the ionization energies and equilibrium geometries of small molecules. It is found that over−all performance of the method is satisfactory for both ionization energies and equilibrium geometries.