An Accurate Numerical Multicenter Integration for Molecular Orbital Theory

摘要

A powerful and accurate numerical three-dimensional integration scheme was developed especially for molecular orbital calculations. A multicenter integral is decomposed into the sum of single-center integrals using nuclear weight functions and calculated using Gaussian quadrature fuels. The decomposed single-center integrands show strong anisotropy. With a careful selection of the Gaussian quadrature rule according to the anisotropy, it is possible to obtain an accuracy of 13 digits with a small number of integration points for the overlap integrals, normalization integrals, and molecular integrals for the hydrogen molecule.