Construction of size-consistent effective Hamiltonians for systems with arbitrary Hilbert space
arXiv:cond-mat/9909317 · doi:10.1088/0953-8984/11/43/316
Abstract
Effective Hamiltonians are usually constructed by using canonical transformations or projection techniques. In contrast to this, we present a method for systems with arbitrary Hilbert space based on the introduction of cumulants. Cumulants guarantee size consistency, a property that is not always evident in other treatments. As a nontrivial example of use the derived method is applied to the strong-coupling limit of the half-filled Hubbard model on a general lattice in arbitrary spatial dimension for which the fourth-order expansion in t/U of the effective Hamiltonian is derived.
arXiv comment9 pages, 5 figures included; accepted for publication in J. Phys.: Condens. Matter