Key Laboratory of Chemical Laser, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China.
J Chem Phys. 2013 Mar 7;138(9):094319. doi: 10.1063/1.4792435.
In this work, the equation-of-motion coupled-cluster approach with spin-orbit coupling (SOC) for ionization potentials (IP) at the singles and doubles level (EOMIP-CCSD) is employed to calculate spectroscopic constants of low-lying states of rare gas dimer ions Kr2(+), Xe2(+), and Rn2(+). Two approaches are proposed to include contributions of triples: (1) energies of these states are calculated by adding the IPs from EOMIP-CCSD and the CCSD(T) energy of the rare gas dimers and (2) CCSD(T) energies without SOC for Rg2(+) are first calculated and energies of these states with SOC are determined subsequently using the SOC matrix between these states. The first approach can provide accurate results for the three most stable states, while overestimates bond lengths for the other states. The second approach has been adopted previously and the SOC matrix element between (2)Σ1∕2 (+) and (2)Π1∕2 states was set to be 1/2 times that of the SOC constant. In our work, the SOC matrix elements are determined from the calculated IPs and reasonable results for these states can be achieved with this approach, which could be useful for experimental works.
在这项工作中，采用了包含自旋轨道耦合（SOC）的单电子和双电子水平的运动方程耦合簇方法（EOMIP-CCSD）来计算稀有气体二聚离子 Kr2(+)、Xe2(+) 和 Rn2(+) 的低能态的光谱常数。提出了两种方法来包含三重态的贡献：（1）通过添加 EOMIP-CCSD 的电离势和稀有气体二聚体的 CCSD(T)能量来计算这些态的能量；（2）首先计算无 SOC 的 Rg2(+)的 CCSD(T)能量，然后使用这些态之间的 SOC 矩阵来确定这些态的 SOC 能量。第一种方法可以为三个最稳定的态提供准确的结果，而对其他态的键长则会高估。第二种方法以前曾被采用过，并且将 (2)Σ1∕2 (+) 和 (2)Π1∕2 态之间的 SOC 矩阵元设置为 SOC 常数的 1/2。在我们的工作中，SOC 矩阵元是从计算的电离势中确定的，并且这种方法可以为这些态提供合理的结果，这对于实验工作可能是有用的。
