三带Hubbard模型中环形电流相的量子蒙特卡罗模拟

Quantum Monte Carlo simulation of the circulating current phases in the Three-Band Hubbard Model

运用约束路径量子蒙特卡罗方法,对二维、三带Hubbard模型中的环形电流相进行数值模拟。在数值模拟过程中定义了表征环流相的不同算符及其关联函数,并且选用合理的模型Hamiltonian量中的参数。通过模拟发现,对应于闭合环形的关联函数在相同距离上要比其他所有没有闭合的关联函数大得多,因此证明在三带Hubbard模型中存在环形电流相。

The circulating current phases in the two - dimensional three - band Hubbard model have been studied numerically by applying the constrained - path quantum Monte Carlo method. Various operators characterizing the circulating current phases are introduced and the correlation functions of those operators are numerically computed. We have found that, within the physical ranges of the model parameters, the correlation functions of hole hoppings giving rise to closed current flow patterns in the circulating current phases are substantially larger than those of hole hoppings corresponding to open current flows. This provides the evidence for the existence of the circulating current phases in the three -band Hubbard model.