Implementation of a variational approach to approximate particle number projection with effective forces

Kamlah's second-order method for approximate particle number projection is applied for the first time to variational calculations with effective force s, High spin states of normal and superdeformed nuclei have been calculated with the finite range density dependent Gogny force for several nuclei. Ad vantages and drawbacks of the Kamlah second-order method as compared to the Lipkin-Nogami recipe are thoroughly discussed. We find that the Lipkin-Nog ami prescription occasionally may fail to find the right energy minimum in the strong pairing regime and that Kamlah's second-order approach though pr oviding better results than the LN one may break down in some limiting situ ations. (C) 2000 Elsevier Science B.V. All rights reserved.