2005/07/19 by Yuchuan Wen, Yu-Chuan Wen, Yue Yu
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.045130
published as Phys. Rev. B 72, 045130 (2005) · 15pages,9figures
openalex publication_date 2005/07/19 · arxiv created 2005/07/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We study the one-band Hubbard model at half filling with hopping asymmetry and its effective model at finite but large U up to the second order of tmix∕U. Two variational wave functions, the resonating valence bond (RVB) wave function and antiferromagnetic (AF) RVB coexisted wave function, are studied by variational Monte Carlo method on L\ifmmode×\else\texttimes\fiL square lattices up to L=12. Based on these two wave functions, the phase diagrams for both models are presented. For the Hubbard model, we find that there is a metal-insulator transition when the hopping parameter tmix which changes the local double occupant vanishes while only a metal-insulator crossover is explored for any finite tmix. For the effective model in which the perturbation expansion is up to the second order of tmix∕U, a clear metal-insulator transition can be identified for both variational wave functions and the phase diagram can be drawn accordingly. In both models, we find that the systems are dominated by AF-RVB wave function when U is large while the RVB wave function is favored when U is small.