Optimal coupled-cluster approximation for the ground-state properties of a spin-boson model |
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Authors: | WH Wong CF Lo |
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Institution: | (1) Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, CN |
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Abstract: | In the present work we have developed an optimal coupled-cluster approximation, which can take care of both the accuracies
of the ground-state energy and the wavefunction estimates, for the ground state of a two-state system coupled to a dispersionless
boson bath. This new approach is also able to give a tight upper bound to the ground-state energy of the system. Up to the
fourth level of this approximation our results show excellent agreement with the numerical exact diagonalization results.
In particular, our results suggest no discontinuous localization-delocalization transition of the two-state system. This is
consistent with the exact result.
Received: 11 March 1998 / Accepted: 23 June 1998 |
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Keywords: | PACS 73 40 Gk Tunneling - 73 20 Jc Delocalization processes - 74 50 +r Proximity effects weaklinks tunneling phenomena and Josephson effets |
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