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摘要: 二维半充满条件下的Hubbard模型,在有限温度下,是否经历一绝缘体—金属相变?在现有的文献中,这一直是一个有争议而又重要的问题。本文采用巨正则量子Monte Carlo方法,计算了二维半充满条件下Hubbard模型的比热和电导率。对不同的库仑排斥势U(2t-8t),比热曲线在高温区出现一个峰,同时电导率在相应温区呈现一突然上升。因此,计算结果支持存在这样一个相变。
Abstract: In the present paper, we attempt to attack the problem of the existence of insulator-metal transition at finite temperature for a 2 dimensional half-filled Hubbard half-filled model. we used the grand Canonical quantum Monte Carlo method to caculate the electrical conductivity and the specific heac of the system. A peak on the specific heat vs temperature curve in high temperature region is observed, and the electrical conductivity curves show a sudden rise in the same temperature region. Thus, our results support that there exists a transition.