Knowledge Bank

Musulin, Mitchell, and $Harriss1$ have shown that wave functions constructed with a variable orbital exponent are as good, with respect to energy predictions, as trial wave functions of equal or greater complexity. The Variation Principle allows one to improve trial wave functions by the inclusion of added parameters. The purpose of the present investigation is to determine if the addition of a single parameter, e.g. Weinbaum-type ionic terms, is as effective for wave functions with a variable orbital exponent as it has been for other trial functions. Results are reported for a two-electron treatment of $Li2$ in the Valence Bond (HLSP) approximation including ionic terms. Some preliminary results for LiH in the same approximations are also given. The latter problem uses two different ionic parameters. All calculations which are reported were performed on an IBM 650 computer.