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arXiv:cond-mat/0311378 · Physical Review B

Exact multielectronic electron-concentration-dependent ground states for disordered two-dimensional two-band systems in the presence of disordered hoppings and finite on-site random interactions

Zsolt Gulácsi

Published Feb 18, 2004• 26 citations
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Abstract

We report exact multielectronic ground states dependent on electron concentration for quantum-mechanical two-dimensional disordered two-band-type many-body models in the presence of disordered hoppings and disordered repulsive finite Hubbard interactions, in fixed lattice topology considered provided by Bravais lattices. The obtained ground states lose their eigenfunction character for independent electron approximation, are perturbatively not connected to the noninteracting but disordered case, and describe a localization-delocalization transition driven by the electron concentration, being highly degenerated and paramagnetic.

DOI
10.1103/physrevb.69.054204

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We study numerically the ground-state properties of the repulsive Hubbard model for spin-1/2 electrons on two-dimensional lattices with disordered on-site energies. The projector quantum Monte Carlo method is used to obtain very accurate values of the ground-state charge density distributions with Np{N}_{p}Np​ and Np+1{N}_{p}+1Np​+1 particles. The difference in these charge densities allows us to study the localization properties of an added particle. The results obtained at quarter filling on finite clusters show that the Hubbard repulsion has a strong delocalizing effect on the electrons in disordered two-dimensional lattices. However, numerical restrictions do not allow us to reach a definite conclusion about the existence of a metal-insulator transition in the thermodynamic limit in two dimensions.
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