Treatment of pairing in small systems by Green functions |
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Authors: | D Zawischa |
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Institution: | 1. Institut für Theoretische Physik der Universit?t Heidelberg, Deutschland
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Abstract: | A finite system of fermions with pairing interaction is treated by the Green function method. It is shown that a finite number of “bound pairs” must be assumed to get the correct properties of the system in that region of the interaction strength where the BCS-solution is incorrect. Also the difference betweenE 0(N+2)?E 0(N) andE 0(N)?E 0(N?2),E 0(N) being the ground state energy of theN-particle system, has to be considered. The formulae derived give an interpolation between the region where perturbation theory applies and the region of validity of the BCS-equations. |
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