Variational cluster approach to correlated electron systems in low dimensions

Phys Rev Lett. 2003 Nov 14;91(20):206402. doi: 10.1103/PhysRevLett.91.206402. Epub 2003 Nov 11.


A self-energy-functional approach is applied to construct cluster approximations for correlated lattice models. It turns out that the cluster-perturbation theory [Phys. Rev. Lett. 84, 522 (2000)]] and the cellular dynamical mean-field theory [Phys. Rev. Lett. 87, 186401 (2001)]] are limiting cases of a more general cluster method. The results for the one-dimensional Hubbard model are discussed with regard to boundary conditions, bath degrees of freedom, and cluster size.