Magnitude and significance of the higher-order reduced density matrix cumulants
Magnitude and significance of the higher-order reduced density matrix cumulants
复制标题
高阶约简密度矩阵累积量的大小和显着性
DOI：
10.1002/qua.21160
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发表时间：
2007
影响因子：
2.2
通讯作者：
J. Herbert
中科院分区：
文献类型：
--
作者：
J. Herbert
使用完整的配置相互作用波函数的Be和LiH，在最小和扩展的基组，我们研究的绝对大小和能量的意义的各种贡献的三电子约化密度矩阵（3-RDM）及其连接（大小一致）的组件，3-RDM累积量（3-RDMC）。最小的基组示出抑制的幅度的3-RDMC在一个人工的方式，而在扩展的基组，3-RDMC矩阵元素往往是相当的幅度相应的3-RDM元素，即使在这种情况下，该结果是不需要的自旋角动量耦合。形式上的考虑表明，这些观察应该推广到高阶p-RDM和p-RDMC（p 3）。这一结果是讨论的背景下的电子结构的方法的基础上收缩薛定谔方程（CSE），作为解决方案的CSE依赖于3-和4-RDM的“重建泛函”，忽略了3-RDMC，4-RDMC，或两者兼而有之。虽然3-RDMC最多只占Be和LiH中总电子能量的0.2%，但它占相关能量的70%，这就提出了CSE是否（以及如何）可以提供有用的计算方法的问题。© 2006 Wiley Periodicals，Inc. Int J Quantum Chem 107：703-711，2007
Using full configuration interaction wave functions for Be and LiH, in both minimal and extended basis sets, we examine the absolute magnitude and energetic significance of various contributions to the three-electron reduced density matrix (3-RDM) and its connected (size-consistent) component, the 3-RDM cumulant (3-RDMC). Minimal basis sets are shown to suppress the magnitude of the 3-RDMC in an artificial manner, whereas in extended basis sets, 3-RDMC matrix elements are often comparable in magnitude to the corresponding 3-RDM elements, even in cases where this result is not required by spin angular momentum coupling. Formal considerations suggest that these observations should generalize to higher-order p-RDMs and p-RDMCs ( p 3). This result is discussed within the context of electronic structure methods based on the contracted Schrodinger equation (CSE), as solution of the CSE relies on 3- and 4-RDM "reconstruction functionals" that neglect the 3-RDMC, the 4-RDMC, or both. Although the 3-RDMC is responsible for at most 0.2% of the total electronic energy in Be and LiH, it accounts for up to 70% of the correlation energy, raising questions regarding whether (and how) the CSE can offer a useful computational methodology. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem 107: 703-711, 2007