Study of twp-gap problem of cuprate superconductors using variation method and BdG equation

考虑到铜酸盐的存在，我们系统地研究了赝隙和d波超导电性的性质，这是阐明高T_c铜酸盐机制的关键。我们主要将变分蒙特卡罗方法应用于Hubbard模型。在接近半填充时，随着相互作用强度的增加，每个态在大约带宽处都表现出与半填充时的Mott跃迁密切相关的交叉。弱关联区域对应于费米液体(BCS超导)相，而强关联区域对应于掺杂Mott绝缘相，在Mott绝缘相中，物理由单占据位和双Holon束缚效应主导。铜酸盐的性质与后者的性质是一致的。

With cuprates in mind, we systematically studied properties of pseudogap and d-wave superconductivity, which are keys to clarify the mechanism of high-Tc cuprates. We mainly applied a variational Monte Carlo method to the Hubbard model. Near half filling, as the interaction strength is increased, every state exhibits, at approximately the band width, a crossover closely related to the Mott transition at half filling. The weakly correlated regime corresponds to a Fermi liquid (BCS superconducting) phase, and the strongly correlate regime to a doped Mott insulating phase, in which physics is dominated by singly occupied sites and the doublon-holon binding effect. Properties of cuprates are consistent to those in the latter regime.