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Comparison of variational and CSE methods to polaron ground-state energy

Qing Chen·Ke-Lin Wang·Yi Wang
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Abstract

Taking the same trial wave function, the ground-state energy of Fröhlich polaron is investigated by variational method and coherent-state expansion (CSE) one, respectively. Within the accuracy to $α^{2}$(the electron-phonon coupling constant), both methods can give the same analytic expressions of polaron ground-state energy as the function of electron-phonon coupling constant. We find that the CSE method can much simplify the calculation and shows more advantages in higher order approximations.

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Qing Chen, Ke-Lin Wang, Yi Wang. 2004-12-19. Comparison of variational and CSE methods to polaron ground-state energy. https://arxiv.org/abs/cond-mat/0412515

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