Mandal, Sheikh Hannan ; Ghosh, Rathindranath ; Mukherjee, Debashis (2001) A non-perturbative cumulant expansion method for the grand partition function of quantum systems Chemical Physics Letters, 335 (3-4). pp. 281-288. ISSN 0009-2614
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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00092...
Related URL: http://dx.doi.org/10.1016/S0009-2614(01)00026-4
Abstract
We present here a non-perturbative cumulant expansion method for computing the grand partition function of quantum systems. It embeds the classical component of grand partition function exactly and treats the quantum contributions by a systematic cluster expansion of the Boltzmann operator. The cluster expansion Ansatz exploits our recently developed notion of thermal normal ordering and a Wick-like expansion formula, which makes evaluation of the thermal trace particularly easy. The thermal normal ordering also confers a finite expansion structure to the equations for the cluster amplitudes. Our formulation provides manifestly extensive free energy, and works very well over a wide range of temperatures and coupling strengths. As an illustrative application, we have computed the grand partition function of an anharmonic oscillator with a pure quartic perturbation.
Item Type: | Article |
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Source: | Copyright of this article belongs to Elsevier Science. |
ID Code: | 21856 |
Deposited On: | 23 Nov 2010 13:06 |
Last Modified: | 05 Mar 2011 11:56 |
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