Correlation energy of the pairing Hamiltonian
Abstract
We study the correlation energy associated with the pair fluctuations in BCS theory. We use a schematic twolevel pairing model and discuss the behavior of the correlation energy across shell closures, including the evenodd differences. It is shown that the random phase approximation (RPA) to the ground state energy reproduces the exact solutions quite well both in the normal fluid and in the superfluid phases. In marked contrast, other methods to improve the BCS energies, such as LipkinNogami method, only work when the strength of a pairing interaction is large. We thus conclude that the RPA approach is better for a systematic theory of nuclear binding energies.
 Publication:

Nuclear Physics A
 Pub Date:
 November 2000
 DOI:
 10.1016/S03759474(00)003432
 arXiv:
 arXiv:nuclth/0003016
 Bibcode:
 2000NuPhA.679..163H
 Keywords:

 Nuclear Theory
 EPrint:
 RevTex, 14 pages, 3 eps figures. The version to appear in Nucl. Phys. A