Correlation energy in bonds. Development of a semiempirical scheme. The CNDO-CMP method

Abstract

An approximate model scheme for taking into account the electron correlation in zero differential overlap (ZDO) methods, which is based on the evaluation of the energy of the correlation of molecular pairs (CMP), has been proposed. A semiempirical quantum-chemical CNDO-CMP method including an SCF calculation of the electronic structure with subsequent consideration of the correlation corrections to the total energy of the system has been developed. The correlation is taken into account during the determination of the parametrization, which is designed to reproduce the equilibrium geometry and the total energy of the molecular system in the ground state and the potential surfaces for dissociative cleavage. Parametrization for calculations of molecular systems containing H, C, O, F, and Ni atoms has been determined; its extension to other elements does not present any fundamental difficulties when the corresponding experimental data are available. The method has been tested in calculations of several molecules and of chemisorption on a model surface of metallic nickel. It has been speculated that the approach developed will be useful in calculations of compounds of transition elements and in the quantum-chemical investigation of chemisorption and reactions on surfaces.