Improvement of Molecular Gaussian Wavefunctions

Gaussian electronic wavefunctions for H, H2+, and H2 are presented and it is shown how they may be improved by, in each case, adding to the basis set a function of the form χ = (ρ − r)lfor r≤ρ = 0 for r>ρ, centered on each nucleus, where r is the distance from the nucleus and ρ and l are parameters which may be chosen to minimize the electronic energy. Such improvement is shown to be greater than that which would be obtained by adding a further Gaussian function to the basis set.