Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples
Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples
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DOI：
10.1063/1.472655
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发表时间：
1996-11
影响因子：
4.4
通讯作者：
L. Visscher;Timothy J. Lee;K. Dyall
中科院分区：
文献类型：
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作者：
L. Visscher;Timothy J. Lee;K. Dyall
给出了相对论开壳CCSD(T)方法的形式，并在计算机程序RELCCSD中实现。该程序可用于2分量或4分量相对论参考波函数的计算，并允许完全包含自旋-轨道耦合。该代码与MOLFDIR程序系统接口。我们用从头算方法计算了Cl、FO、ClO、O+2和O−2的精细结构分裂，发现三重修正对氯原子分裂有很大的贡献，其值在实验值的23 cm−1以内。分子结果在实验值的4厘米−-1范围内。FO的预测值为−195±4 cm−1，与实验符合较好。
The formalism for a relativistic open‐shell CCSD(T) method is presented and implemented in a computer program, RELCCSD. The code can be used for calculations with 2‐ or 4‐component relativistic reference wave functions and allows a full inclusion of the spin–orbit coupling. The code is interfaced to the MOLFDIR program system. We illustrate its use with ab initio calculations of the fine structure splittings of Cl, FO, ClO, O+2, and O−2. The triples correction is found to make a large contribution to the Cl atom splitting, which is within 23 cm−1, of the experimental value. The molecular results are within 4 cm−1 of the experimental values where these are available. The value for FO is predicted to be −195±4 cm−1, in good agreement with experiment.