Magnetism in the Hubbard model-An improved treatment
摘要
We propose a new treatment of the Hubbard model that is based both on the coherent-potential approximation (CPA) and the virtual-crystal approximation (VCA). It is well known that the equilibrium found using the one-particle CPA Green's functions does not predict an ordered magnetic ground state, while Stoner's mean-field treatment, which is equivalent to the VCA on the Hubbard model, does so for a wide range of parameters. A hybrid treatment, the tau-CPA, is developed, in which a particle is assumed to be scattered from an array of static opposite spins for a time tau related to the inverse of the band width. The propagation is treated in the CPA over this period; thereafter the particle sees the time-averaged effect of the scatterers and hence can be treated in the VCA. This model, with suitable approximations, does predict magnetism for a modified Stoner criterion.
引用
@article{arxiv.cond-mat/0304081,
title = {Magnetism in the Hubbard model-An improved treatment},
author = {A. Uldry and R. J. Elliott},
journal= {arXiv preprint arXiv:cond-mat/0304081},
year = {2007}
}