arXiv:cond-mat/9810371 · Physical review. B, Condensed matter
Incremental expansions for the ground-state energy of the two-dimensional Hubbard model
Jiri Malek, Sergej Flach A, K. Kladko
Abstract
A generalization of Faddeev's approach of the three-body problem to the many-body problem leads to the method of increments. This method was recently applied to account for the ground-state properties of Hubbard-Peierls chains [J. Malek, K. Kladko, and S. Flach, JETP Lett. 67, 1052 (1998)]. Here we generalize this approach to two-dimensional square lattices and explicitly treat the incremental expansion up to third order. Comparing our numerical results with various other approaches (Monte Carlo, cumulant approaches) we show that incremental expansions are very efficient because good accuracy with these approaches is achieved treating lattice segments composed of eight sites only.