Investigation of LCAO approximation for diatomic molecules in Hartree-Fock method

Abstract

Abstract It was shown that the use of the conventional two-center LCAO approximation in the Hartree-Fock method results in non-equivalent description of the asymptotic properties of the total molecular wave function and MO’s in the directions of the united and separated atoms. This leads to a deviation of the Hartree-Fock potential curve calculated with using this approximation from that one obtained without it and which is growing with decreasing the internuclear separation. Additionally, the method has been developed for an investigation of the quality of the asymptotic behavior of the potential curves by analyzing their analytical properties. The direct comparison of the Hartree-Fock potential curves of CH and OH molecules obtained with and without LCAO approximation, as well an application of the proposed method for investigation of the analytical properties of them, display this shortcoming of the conventional two-center LCAO approximation.