Quantum Periodic Cluster Methods for Strongly-Correlated Electron Systems

Abstract

Quantum periodic cluster methods for strongly-correlated electron systems are reformulated and developed. The real lattice is divided into a superlattice of clusters. The reformulation and development are based on a canonical transformation, which periodizes the fermions in the cluster space. The dynamical cluster approximation and the cellular dynamical mean field theory are related to each other through the canonical transformation. A cluster perturbation theory with periodic boundary conditions is developed. The periodic cluster perturbation theory is found to converge rapidly with corrections O(1/L(c)(2)), where L(c) is the linear size of the clusters, whereas the ordinary cluster perturbation theory converges with corrections O(1/L(c)).