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arXiv · 1510.05857

Cumulant $t$-expansion for strongly correlated fermions

A. K. Zhuravlev
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Abstract

A systematic nonperturbative scheme is implemented to calculate the ground state energy for a wide class of strongly correlated fermion models. The scheme includes: (a) method of automatic calculations of the cumulants of the model Hamiltonian; (b) method of the ground state energy calculation from these cumulants using the $t$-expansion proposed by Horn and Weinstein [Phys. Rev. D \textbf{30}, 1256 (1984)] with new procedure of its extrapolation to $t\rightarrow\infty$. As an example of application of the method all cumulants up to the 8-th order for spinless fermion model are calculated exactly, and converging sequences of approximations to the ground state energy are obtained for one-, two- and three-dimensional versions of the model.

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A. K. Zhuravlev. 2015-10-20. Cumulant $t$-expansion for strongly correlated fermions. https://doi.org/10.1016/j.physleta.2016.04.003

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