Abstract
A procedure used by McQuarrie and Hirschfelder to obtain approximate solutions of the first‐order Hirschfelder–Silbey equations for the special case of H2+ is generalized. The contribution due to exchange is determined by applying the Unsöld approximation to the spectral expansion of the first‐order function and then determining the closure parameter variationally. The energy is found to be independent of the closure parameter through second order.