Two-Dimensional Hubbard Model : Metal Insulator Transition Studied by Monte Carl Calculation

概要

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The Hubbard model on a square lattice in the ground state is investigated. Variousaspects of Molt transition at half-filling are clarified from the quantum Monte Carlostudy. Critical exponents of tlte transition for charge and spin correlations are esti-mated. For the doping concentration i, the charge susceptibility is prc>portional tod -' indicating the divergence of charge mass f or l>'-+ 0, while the spin susceptibility isalways fimaite and not singular near d=0. Several theoretical consequences of theabove results are discussed. Incommensurate peak amplituade of spirx correlationscales as (i - 'c)-' with i.< 0.01 in disagreement with RPA results In (i - J.). The an-tiferromagnetic order at the half-filling also shows strong correlation character and isnot sensitive to the shape of the fermi surface, while the incommensurate peak ob-served away from the half-filling is sensitively suppressed by the loss of partial nestingconsistently with the weak coupling picture. Comparisons with experimental indica-lions of high-7'. oxides are made.
社団法人日本物理学会の論文
1992-09-15