Theory of fermion systems with attractive interactions: exact solution of the bcs reduced hamiltonian
Tóm tắt
A Barden-Cooper-Schrieffer type of reduced Hamiltonian, with an arbitrary pairing interaction is studied with the help of the method of temperature-dependent Green’s functions. The equations are solved by expansion in powers ofN
−1, whereN is the number of particles, and elements of a proof are given that these equations possess at most three classes of solutions : the normal solution in which all correlations are absent (to order unity), a solution which requires in addition two particle correlations and corresponds to that of BCS, and a solution in which all correlations must be retained. Only the BCS case is treated in this paper. A new derivation of the complete thermodynamics is given. By considering the perturbation by an external field, one is led to the underlying matrix structure of the theory.
Tài liệu tham khảo
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