Comparison of the polarizabilities and hyperpolarizabilities obtained from finite basis set and finite difference Hartree–Fock calculations for diatomic molecules: II. Refinement of basis sets and grids for hyperpolarizability calculations

Abstract

In a previous paper, we have made a comparison of the accuracy with which the electric dipole polarizability αzz and hyperpolarizability βzzz can be calculated by using either the finite basis set approach (the algebraic approximation) or the finite difference method in calculations for the ground states of the H2, LiH, BH and FH molecules, at their respective experimental equilibrium geometries, within the Hartree–Fock model. A re-examination of the hyperpolarizability of the BH molecule shows it to be very sensitive both to the choice of grid employed in the finite difference Hartree–Fock calculation and the construction of the basis set used in the matrix Hartree–Fock study. A new comparison of finite difference and finite basis set hyperpolarizabilities for the BH molecule is made, together with new calculations for the LiH and FH ground states.