中文摘要：

考虑了近邻格点相互作用后,Bose-Hubbard模型（BHM）变为拓展的Bose-Hubbard模型（EBHM）。在该模型中,有一个新的项：原子对隧穿项,它就是文章研究的重点。文章利用密度矩阵重整化群（DMRG）的方法处理EBHM,给出零温下的一维相图,并着重研究了对隧穿项对相图的影响。根据Luttinger液体理论及关联函数随格点间距的衰退,得到Berezinskii-Kosterlitz-Thouless相变临界点。

英文摘要：

By taking nearest-neighbor interaction into account, Bose-Hubbard model（BHM） is turned into an extended Bose-Hubbard model（EBHM）. This model has a novel term：atom-pair tunneling, which is the re- search key point of this paper. In this paper EBHM is investigated using the density-matrix renormalization group（DMRG）. At zero temperature one-dimensional phase diagram is achieved. We mainly study the influ- ence of pair-tunneling on phase diagram. Furthermore, according to Luttinger liquid theory and the decay of correlation function with the interval between sites,the critical point of the Berezinskii-Kosterlitz-Thouless transition is obtained.