ETH Zurich, Laboratorium für Physikalische Chemie, Wolfgang-Pauli-Str. 10, CH-8093 Zurich, Switzerland.
J Chem Phys. 2011 Jun 14;134(22):224101. doi: 10.1063/1.3596482.
We present a procedure to construct a configuration-interaction expansion containing arbitrary excitations from an underlying full-configuration-interaction-type wave function defined for a very large active space. Our procedure is based on the density-matrix renormalization group (DMRG) algorithm that provides the necessary information in terms of the eigenstates of the reduced density matrices to calculate the coefficient of any basis state in the many-particle Hilbert space. Since the dimension of the Hilbert space scales binomially with the size of the active space, a sophisticated Monte Carlo sampling routine is employed. This sampling algorithm can also construct such configuration-interaction-type wave functions from any other type of tensor network states. The configuration-interaction information obtained serves several purposes. It yields a qualitatively correct description of the molecule's electronic structure, it allows us to analyze DMRG wave functions converged for the same molecular system but with different parameter sets (e.g., different numbers of active-system (block) states), and it can be considered a balanced reference for the application of a subsequent standard multi-reference configuration-interaction method.
我们提出了一种从非常大的活性空间定义的全组态相互作用型波函数中构建包含任意激发的组态相互作用展开的方法。我们的方法基于密度矩阵重整化群（DMRG）算法，该算法以约化密度矩阵的本征态为基础提供了计算多粒子希尔伯特空间中任何基态系数所需的信息。由于希尔伯特空间的维数与活性空间的大小呈二项式缩放，因此采用了复杂的蒙特卡罗抽样程序。这种抽样算法也可以从任何其他类型的张量网络态构建这种组态相互作用型波函数。所得到的组态相互作用信息有几个用途。它提供了分子电子结构的定性正确描述，它允许我们分析为相同分子系统但具有不同参数集（例如，不同数量的活性系统（块）态）而收敛的 DMRG 波函数，并且可以作为随后应用标准多参考组态相互作用方法的平衡参考。
