Spin adapted restricted Hartree–Fock reference coupled cluster theory for open shell systems
Spin adapted restricted Hartree–Fock reference coupled cluster theory for open shell systems
复制标题
开壳系统的自旋适应受限 Hartree-Fock 参考耦合簇理论
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
I. Hubač
中科院分区：
文献类型：
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作者：
P. Neogrády;M. Urban;I. Hubač
建立了具有单一受限Hartree-Fock参考行列式的开壳体系的有效计算的耦合簇（CC）方法。我们在之前的工作中描述了自旋自适应，旨在消除耦合团簇（CC）振幅和CC能量中的自旋污染，用于单激发和双激发耦合团簇（CCSD）方法的线性和非线性版本。我们给出了适应方法和非适应方法的结果比较。在消除自旋污染的同时，我们的自旋适应产生了CC方程，减少了CC振幅的数量和算术运算的数量，从而使计算时间与类似的闭壳计算相当。全自旋适应CC方法的复杂之处在于，单个自旋状态需要特定的自旋适应激发，因此对于每个自旋状态，都需要不同的实现。有可能定义一个非常有效的近似值……
The coupled clusters (CC) method for effective calculations of open shell systems with the single restricted Hartree–Fock (ROHF) reference determinants is formulated. We apply the spin adaptation described in our previous work, aimed at removing the spin contamination in both coupled cluster (CC) amplitudes and CC energy, both for the linear and nonlinear versions of the single and double excitation coupled cluster (CCSD) method. We give a comparison of results with adapted and nonadapted methods. Together with the elimination of the spin contamination, our spin adaptation yields CC equations, which reduce the number of CC amplitudes and the number of arithmetical operations, which results in computational time comparable with analogous closed shell calculations. The complication in the full spin adapted CC method is that individual spin states require specific spin adapted excitations, so that for every spin state, a different implementation is needed. It is possible to define a very effective approximat...