Pseudoatom expansions of the H2 electron density

Abstract

Representations of a high-quality molecular electron density are studied. An evaluation of restricted radial functions is made using a least-squares figure of merit, the molecular quadrupole moment, the electric field at the nucleus, the electric-field gradient at the nucleus, an approximate energy and difference-density maps. It is concluded that for an accurate representation expansions to the quadrupole level or higher are needed with either single-term Slater-type radial functions having all exponents optimized, or two-term functions with a common exponent optimized. Generalized scattering factors from the restricted radial functions are not good approximations to those from completely flexible radial functions, but nevertheless give good property values.