College of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China.
J Chem Phys. 2012 May 7;136(17):174102. doi: 10.1063/1.4704894.
We report implementation of the equation of motion coupled-cluster approach for ionized states (EOMIP-CC) with spin-orbit coupling (SOC) using closed-shell state as reference in this work. Ionization potentials (IPs) are calculated in the ionized 1h and 2h1p space with EOM at the CC singles (CCS) as well as the CC singles and doubles levels (CCSD). In this EOMIP-CC approach, SOC is included either in both the CC and EOM steps or only in the EOM step. It should be noted that IPs provided by the EOMIP-CC approach with SOC included only in the EOM step are not size-intensive. Time-reversal symmetry and spatial symmetry are exploited for D(2h) and its subgroups to reduce computational effort. All these approaches have been shown to be able to afford acceptable estimates for SOC splittings. The EOMIP-CCSD with SOC included only in the EOM step can provide reasonable IPs for systems containing up to 5th row elements. On the other hand, the EOMIP-CCS approach with SOC included in both CC and EOM steps could not predict a bounded (2)∑(g) (+) state for I(2) (+) and should be used with care.
我们在这项工作中报告了用方程运动耦合簇方法（EOMIP-CC）结合自旋轨道耦合（SOC）来处理电离态，其中使用闭壳层态作为参考。我们在电离的 1h 和 2h1p 空间中使用 EOM 在 CC 单重态（CCS）以及 CC 单重态和双重态（CCSD）计算了电离势（IP）。在这种 EOMIP-CC 方法中，SOC 要么同时包含在 CC 和 EOM 步骤中，要么只包含在 EOM 步骤中。需要注意的是，只在 EOM 步骤中包含 SOC 的 EOMIP-CC 方法提供的 IP 不是密集型的。时间反转对称性和空间对称性被用于 D(2h)及其子群，以减少计算工作量。所有这些方法都被证明能够提供 SOC 分裂的可接受估计。只在 EOM 步骤中包含 SOC 的 EOMIP-CCSD 可以为包含最多 5 个元素的系统提供合理的 IP。另一方面，在 CC 和 EOM 步骤中同时包含 SOC 的 EOMIP-CCS 方法不能预测 I(2) (+)的有界 (2)∑(g) (+)态，因此应该谨慎使用。
