arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1002.2449cond-mat.str-elcond-mat.other
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用一维玻色-哈伯德模型对变分聚类方法进行基准检验

Benchmarking the variational cluster approach by means of the one-dimensional Bose-Hubbard model

Michael Knap, Enrico Arrigoni, Wolfgang von der Linden

摘要:

研究和讨论了玻色多体系统变分簇方法关于变分参数空间、簇大小和参考系边界条件的收敛性。具体地说,变分集团的方法被应用到一维玻色-哈伯德模型,它表现出量子相变从莫特超流相。为了基准的变分聚类方法,相边界划定的第一莫特瓣的结果进行了比较,基本上精确的密度矩阵重整化群数据。此外,静态量,如基态能量和单粒子密度矩阵进行了比较,高阶强耦合微扰理论的结果。对于具有开边界条件的参考系,通过附加的变分参数扩展变分参数空间,该变分参数允许参考系上的更均匀的粒子密度,从而显著地改善了结果。事实证明,变分聚类方法产生准确的结果,相对较低的计算工作量的光谱以及静态性能的一维玻色-哈伯德模型,即使在第一莫特瓣的相关效应是最明显的尖端。

英文摘要:

Convergence properties of the variational cluster approach with respect to the variational parameter space, cluster size, and boundary conditions of the reference system are investigated and discussed for bosonic many-body systems. Specifically, the variational cluster approach is applied to the one-dimensional Bose-Hubbard model, which exhibits a quantum phase transition from Mott to superfluid phase. In order to benchmark the variational cluster approach, results for the phase boundary delimiting the first Mott lobe are compared with essentially exact density matrix renormalization group data. Furthermore, static quantities, such as the ground state energy and the one-particle density matrix are compared with high-order strong coupling perturbation theory results. For reference systems with open boundary conditions the variational parameter space is extended by an additional variational parameter which allows for a more uniform particle density on the reference system and thus drastically improves the results. It turns out that the variational cluster approach yields accurate results with relatively low computational effort for both spectral as well as static properties of the one-dimensional Bose-Hubbard model, even at the tip of the first Mott lobe where correlation effects are most pronounced.

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