扩展Hubbard模型的关联函数

Correlation Function of the Extended Hubbard Model

在连续化极限情况下把量子一维格点扩展Ｈｕｂｂａｒｄ模型变换为连续的费米场．进而采用玻色化方法得到模型的玻色场形式．比较玻色化扩展Ｈｕｂｂａｒｄ模型和玻色化ＸＸＺ链，导出了两者的等价性．利用ＸＸＩ链模型的严格解和玻色化解的关系，计算了格点扩展Ｈｕｂｂａｒｄ模型的关联函数，给出了格点扩展Ｈｕｂｂａｒｄ模型的相图．当模型的相互作用发生变化时，扩展Ｈｕｂｂａｒｄ模型会历经四个不同的相，并在相区分界线处存在不同类型的相变．最后，提出了扩展Ｈｕｂｂａｒｄ模型相图中电荷密度波和自旋密度波相边界漂移的合理解释．

In the continuous limit, the quantum one dimensional extended Hubbard lattice model with half filled band was transformed into the ferimion field. By using the bosonization method, the extended Hubbard model was then changed to the bosonized field form. Basing on the concepts of mapping, by relating the extended Hubbard model with the XXZ chain, the correlation functions of the extended Hubbard model were calculated and the phase diagram of the lattice model was obtained. Its phase diagram shows that there exist four different phase regions and different transitions with the varying of the interactions. A successful explanation of the deviation of the bounary line between charge density wave and spin density wave was given.