Cusped-gaussian wave functions

Abstract

The single-excitation configuration interaction method is used to calculate the spin density at the nucleus in the Li atom and the LiH⁺ molecular ion. A variety of cusped-gaussian, all-gaussian and Slater function basis sets are compared. It is shown that whilst it is difficult to obtain reliable values for the spin density with conventional gaussian basis sets, the cusped-gaussian basis can give values of the properties at a nucleus that are very similar to those obtained with a Slater function basis. It is shown that it is essential for accurate work to ensure that the basis is highly flexible in the region close to a nucleus.