一维扩展离子Hubbard模型的相图研究

Phase diagram of the one-dimensional extended ionic Hubbard model

应用密度矩阵重整化群方法,研究了存在交错离子势△时一维半满扩展Hubbard模型的相图.通过计算关联函数、结构因子、位置算符等方法,描绘了从Mott绝缘体-键有序绝缘体-Band绝缘体的特性并给出了精确的相边界.研究发现:中间的键有序绝缘体相在相图中占据了很小的一部分区域,当存在离子势△的情况下,这个区域将会有所增大;而当相互作用足够强时,这个中间相消失.给出了离子Hubbard模型(最近邻电子-电子相互作用=0)的相图.

We use a density-matrix renormalization group method to study quantitatively the phase diagram of the half-filled one-dimensional （1D） extended Hubbard model in the presence of a staggered ionic potential △. An extensive finite-size scaling analysis is carried out on the relevant structure factors and localization operator to characterize the Mott-insulator （MI）-bond-ordered insulator （BOI）-band-insulator （BI） transitions. The intermediate BOI phase occupies a small region of the phase diagram, and this region is enlarged in the presence of △. In addition, the phase diagram of ionic Hubbard （the nearest-neighbor electron-electron interaction V = 0） is also given.