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arXiv 1202.2744cond-mat.dis-nn
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库仑玻璃:平均场与蒙特卡罗结果的比较

Coulomb Glasses: A Comparison Between Mean Field and Monte Carlo Results

E. Bardalen, J. Bergli, Y. M. Galperin

摘要:

最近提出了库仑玻璃平衡和输运性质的局域平均场论[A. Amir等人,B 77,165207(2008); 80,245214(2009)]。我们比较这个理论的预测动态蒙特卡罗模拟的结果。在一个热平衡状态下,我们比较了态密度和占据几率。我们还研究了不同状态之间的跃迁速率,发现平均场速率低估了某一类重要的跃迁。我们提出修改后的利率将用于平均场的方法,考虑到在这个意义上的最低水平的相关性,过渡只发生从一个被占领到一个空的网站。我们发现,这种修改占大多数的平均场和蒙特卡罗速率之间的差异。的线性响应电导示出表现出Efros-Shklovskii行为的平均场和蒙特卡罗方法,但平均场方法强烈低估了在低温下的电流。当使用修改后的速率时,实现了更好的一致性。

英文摘要:

Recently a local mean field theory for both eqilibrium and transport properties of the Coulomb glass was proposed [A. Amir et al., Phys. Rev. B 77, 165207 (2008); 80, 245214 (2009)]. We compare the predictions of this theory to the results of dynamic Monte Carlo simulations. In a thermal equilibrium state we compare the density of states and the occupation probabilities. We also study the transition rates between different states and find that the mean field rates underestimate a certain class of important transitions. We propose modified rates to be used in the mean field approach which take into account correlations at the minimal level in the sense that transitions are only to take place from an occupied to an empty site. We show that this modification accounts for most of the difference between the mean field and Monte Carlo rates. The linear response conductance is shown to exhibit the Efros-Shklovskii behaviour in both the mean field and Monte Carlo approaches, but the mean field method strongly underestimates the current at low temperatures. When using the modified rates better agreement is achieved.

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