Methods for Calculating Ground-State Correlations of Vibrational Nuclei

Abstract
A general method for studying ground-state correlations is described. It is shown that the usual random-phase approximation overestimates depletion of the uncorrelated state by a factor of 2, in agreement with a result found by Rowe, using the number-operator method. The correctness of the latter method is then independently verified. A precise division of the ground-state correlations into collective and noncollective parts is shown for a simple model, but it is argued that the division is not valid in general.