Constrained-path quantum Monte Carlo simulations of the zero-temperature disordered two-dimensional Hubbard model
Abstract
We study the effects of disorder on long-range antiferromagnetic correlations in the half-filled, two dimensional, repulsive Hubbard model at T=0. A mean field approach is first employed to gain a qualitative picture of the physics and to guide our choice for a trial wave function in a constrained path quantum Monte Carlo (CPQMC) method that allows for a more accurate treatment of correlations. Within the mean field calculation, we observe both Anderson and Mott insulating antiferromagnetic phases. There are transitions to a paramagnet only for relatively weak coupling, U < 2t in the case of bond disorder, and U < 4t in the case of on-site disorder. Using ground-state CPQMC we demonstrate that this mean field approach significantly overestimates magnetic order. For U=4t, we find a critical bond disorder of Vc = (1.6 +- 0.4)t even though within mean field theory no paramagnetic phase is found for this value of the interaction. In the site disordered case, we find a critical disorder of Vc = (5.0 +- 0.5)t at U=4t.
Cite
@article{arxiv.cond-mat/0102172,
title = {Constrained-path quantum Monte Carlo simulations of the zero-temperature disordered two-dimensional Hubbard model},
author = {M. Enjalran and F. Hebert and G. G. Batrouni and R. T. Scalettar and Shiwei Zhang},
journal= {arXiv preprint arXiv:cond-mat/0102172},
year = {2009}
}
Comments
Revtex, 13 pages, 15 figures. Minor changes to title and abstract, discussion and references added, figures 5, 6, 8, 9 replaced with easier to read versions