Optimizing linked-cluster expansions by white graphs.
Optimizing linked-cluster expansions by white graphs.
复制标题
通过白色图优化链接集群扩展
DOI：
10.1103/physreve.92.022118
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
K.P. Schmidt
中科院分区：
文献类型：
--
作者：
K. Coester;K.P. Schmidt
我们介绍了一个white-graph expansionfor方法的扰动连续酉变换时，实施为一个链接的集群扩展。在白色图的扩展背后的基本思想是通过利用二次量子化中与模型无关的有效哈密顿量和相关的固有团簇可加性在计算期间执行优化簿记。这种方法被证明是特别适合于具有许多耦合常数的微观模型，因为相关图形的总数大大减少。白图展开是一个二维量子自旋耦合两legladders模型的例子。
We introduce awhite-graph expansionfor the method of perturbative continuous unitary transformations when implemented as a linked-cluster expansion. The essential idea behind an expansion in white graphs is to perform an optimized bookkeeping during the calculation by exploiting the model-independent effective Hamiltonian in second quantization and the associated inherent cluster additivity. This approach is shown to be especially well suited for microscopic models with many coupling constants, since the total number of relevant graphs is drastically reduced. The white-graph expansion is exemplified for a two-dimensional quantum spin model of coupled two-legladders.