Multiple scattering expansions in several particle dynamics

“…39 and references therein͒. These expansions ͑e.g., Fadeev equations͒ are suited for a small number of particles; therefore, they cannot be easily modified to condensed-matter problems.…”

Section: Elimination Of the Repeated Collisionsmentioning

confidence: 99%

“…38,39 With this technically minor modification the T-matrix approximation becomes applicable to the superconducting state. In the ͑conventional͒ normal metal, corrections are of the order of 1 / ⍀, where ⍀ is a system volume, but in the superconductor these corrections are of the order of unity.…”

Section: Introductionmentioning

confidence: 99%

Multiple scattering corrections to theT-matrix approximation: Unified theory of normal and superconducting states

Lipavský

2008

Phys. Rev. B

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We present unified theory of both normal and superconducting states based on the fully self-consistent T-matrix approximation. We argue that the failure of the customary T-matrix approach below the critical temperature is caused by nonphysical repeated collisions. We eliminated the repeated collisions from the Galitskii-Feynman approximation. Obtained corrections are proportional to the inverse volume in the normal state and, thus, vanish in the thermodynamical limit. In the superconducting state these corrections remain finite and describe the Bardeen-Cooper-Schrieffer ͑BCS͒ gap. The T-matrix approach goes beyond mean-field BCS theory. It is, thus, well suited for studies of the systems with large fluctuations such as the BCS-Bose-Einstein-condensate crossover or size effects in small metallic grains and the nuclear matter.

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“…pd scattering was worked out by Glauber and Franco (1966) and further refined by, for instance, Michael and Wilkin (1969), Franco and Glauber (1969), Alberi and Bertocchi (1969), and Joachain and Quigg (1974).…”

Section: S9mentioning

confidence: 99%