标题： 面心和体心立方晶格上扩展 Hubbard-Holstein 模型中轻型和超轻型双极化子的量子蒙特卡罗模拟 显示英文标题

标题： Quantum Monte Carlo simulation of light and superlight bipolarons in extended Hubbard-Holstein models on face- and body-centered-cubic lattices

摘要： 超轻双极子对在面心立方（FCC）和体心立方（BCC）晶格中由电子-声子相互作用（EPIs）驱动，使用连续时间路径积分量子蒙特卡罗（QMC）算法进行研究。 EPIs 是 Holstein 和扩展的 Holstein 类型，并包括一个 Hubbard 相互作用。 计算了与双极子相关的声子数、倒质量以及半径，并用于构建双极子配对的相图（识别配对为晶格间双极子和晶格内双极子的区域）。 从倒质量可以确定，对于扩展相互作用，在 BCC 和 FCC 晶格中形成的晶格间双极子存在一个轻配对区域。 在大声子频率和大库仑排斥下，扩展模型中的晶格间双极子由于一阶跃迁效应而变得超轻。 估计了这些对的玻色-爱因斯坦凝聚的转变温度。 确定晶格间双极子与高转变温度区域有关。 显示英文摘要

摘要： Superlight pairing of bipolarons driven by electron-phonon interactions (EPIs) in face-center-cubic (FCC) and body-center-cubic (BCC) lattices is investigated using a continuous-time path-integral quantum Monte Carlo (QMC) algorithm. The EPIs are of the Holstein and extended Holstein types, and a Hubbard interaction is also included. The number of phonons associated with the bipolaron, inverse mass, and radius are calculated and used to construct a phase diagram for bipolaron pairing (identifying the regions of pairing into intersite bipolarons and onsite bipolarons). From the inverse mass it is determined that for the extended interaction, there is a region of light pairing associated with intersite bipolarons formed in both BCC and FCC lattices. Intersite bipolarons in the extended model at large phonon frequency and large Coulomb repulsion become superlight due to first order hopping effects. The transition temperature of Bose--Einstein condensates of these pairs is estimated. It is determined that intersite bipolarons are associated with regions of high transition temperatures.