Rules for developing basis sets for the accurate computation of hyperpolarizabilities: Applications to He, H2, Be, Ne, F−, and HF

Abstract

Various procedures for designing basis sets to be used in the computation of high-quality wave functions have been considered. The most satisfactory results for the polarizability and hyperpolarizabilities of He, H2, Be, Ne, F−, and HF were obtained using the core basis sets of van Duijneveldt, augmented by 7f1(l+1)5f2(l+2), where f1 and f2 are polarization Gaussian-type functions which are energy optimized and l defines the symmetry of the highest occupied subshell of the atom. Subsequently, simple rules, like replacing the 2s and 2f functions having the largest exponents with an equal number of orbitals of the same symmetry, the exponents of which form a geometric or even-tempered sequence with the two most diffuse exponents, have been used. Correlation effects are taken into account using fourth-order Mo/ller–Plesset perturbation theory.