Projected Quasi-particle Perturbation theory

Abstract

The BCS and/or HFB theories are extended by treating the effect of four quasi-particle states perturbatively. The approach is tested on the pairing hamiltonian, showing that it combines the advantage of standard perturbation theory valid at low pairing strength and of non-perturbative approaches breaking particle number valid at higher pairing strength. Including the restoration of particle number, further improves the description of pairing correlation. In the presented test, the agreement between the exact solution and the combined perturbative + projection is almost perfect. The proposed method scales friendly when the number of particles increases and provides a simple alternative to other more complicated approaches.

References in corpus (5)

• Beyond the relativistic mean-field approximation (II): configuration mixing of mean-field wave functions projected on angular momentum and particle number
• Thermodynamics of pairing in mesoscopic systems
• Accuracy of BCS-based approximations for pairing in small Fermi systems
• Number-conserving theory of nuclear pairing gaps: a global assessment
• Description of Pairing correlation in Many-Body finite systems with density functional theory

Cited by in corpus (13)

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• Fluctuating parts of nuclear ground state correlation energies
• Anomalous propagators and the particle-particle channel: Hedin's equations
• On the description of two-particle transfer in superfluid systems
• Combining symmetry breaking and restoration with configuration interaction: extension to z-signature symmetry in the case of the Lipkin Model
• Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory
• Symmetry Restoration in Mixed-Spin Paired Heavy Nuclei
• Extension of time-dependent Hartree-Fock-Bogoliubov equations