Structure of the number projected BCS wave function
arXiv:1603.00642 · doi:10.1103/PhysRevC.93.034313
Abstract
We study the structure of the number projected BCS (PBCS) wave function in the particle-hole basis, displaying its similarities with coupled clusters theory (CCT). The analysis of PBCS together with several modifications suggested by the CCT wave function is carried out for the exactly solvable Richardson model involving a pure pairing hamiltonian acting in a space of equally-spaced doubly-degenerate levels. We point out the limitations of PBCS to describe the non-superconducting regime and suggest possible avenues for improvement.
arXiv comment6 pages, 4 figures. To be published in Phys. Rev. C
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- Variational theory combining number-projected BCS and coupled-cluster doubles
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