二维半充满Hubbard模型有限温度下绝缘体──金属相变的研究

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。 关键词：

INSULATOR-METAL TRANSITION OF THE 2-D HALF-FILLED HUBBARD MODEL AT FINITE-TEMPERATURES

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.