Gaussian Quadrature Xα Method for Self-Consistent Hartree-Fock-Slater Equation. I. Application to the Total Energy Calculation of Diatomic Molecule

Abstract

In order to improve the accuracy for the Diophantine integration scheme in the discrete variational Xα method, which makes orbital calculations with non muffin-tin potential for large systems, it is proposed to use Gaussian quadrature (GQ) for integrating the Hamiltonian and overlap matrix elements. The values for these quantities show very good convergence with a relatively small number of sampling points. The total energy calculations as well as orbital energy calculations are carried out for diatomic CO and C₂ molecules. The calculated dissociation energies reasonably agree with experimental data. Equilibrium bond distances, however, are somewhat larger than the experimental value. The present method has been applied to diatomic FeO molecule. The bond distance and bond energy for this molecule are discussed.