Hirano Tsuneo, Okuda Rei, Nagashima Umpei, Jensen Per
Department of Chemistry, Faculty of Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
J Chem Phys. 2007 Jul 7;127(1):014303. doi: 10.1063/1.2723110.
The ground and low-lying excited states of CoCN have been studied by ab initio multireference single and double excitation configuration interaction (MR-SDCI) calculations with Davidson's correction Q and Cowan-Griffin's relativistic corrections. The electronic ground state of CoCN is (3)Phi(i) and the equilibrium geometry is linear with bond lengths of r(e)(Co-C)=1.8540 A and r(e)(C-N)=1.1677 A, substantially different from the experimentally derived values of r(0)(Co-C)=1.8827(7) A and r(0)(C-N)=1.1313(10) A. The first excited state is (3)Delta(i), separated from the ground state by 727 cm(-1). Larger dynamical electron correlation energy for the low-spin (3)Phi state than for the high-spin (5)Phi state makes the (3)Phi state to be the ground state, which is discussed in terms of the differences in natural orbitals. A new spin-orbit interaction scheme between the X (3)Phi(i) and 1 (3)Delta(i) states is proposed.
通过采用戴维森校正Q和考恩-格里芬相对论校正的从头算多参考单双激发组态相互作用（MR-SDCI）计算，对CoCN的基态和低激发态进行了研究。CoCN的电子基态为(3)Φ(i)，平衡几何构型为线性，键长r(e)(Co-C)=1.8540 Å，r(e)(C-N)=1.1677 Å，与实验得出的r(0)(Co-C)=1.8827(7) Å和r(0)(C-N)=1.1313(10) Å值有很大差异。第一激发态为(3)Δ(i)，与基态的能量差为727 cm(-1)。低自旋(3)Φ态的动态电子相关能比高自旋(5)Φ态的大，这使得(3)Φ态成为基态，从自然轨道的差异方面对此进行了讨论。提出了一种X (3)Φ(i)和1 (3)Δ(i)态之间新的自旋-轨道相互作用方案。
