A CASSCF and CASPT2 study on the excited states of s-trans-formaldazine

作者：Luo Cheng; Duan Xue mei; Liu Jing yao; Li Ze sheng^*

来源：Journal of Physical Chemistry A, 2008, 112(38): 8979-8985.

DOI：10.1021/jp805081h

The low-lying excited states of s-trans-formaldazine (H2C = N-N = CH2) have been investigated using the complete active space self-consistent field (CASSCF) and the multiconfigurational second-order perturbation (CASPT2) methods. The vertical excitation energies have been calculated at the state-average CASSCF and multistate CASPT2 levels employing the cc-pVTZ basis set. The photodissociation mechanisms starting from the S, state have been determined. The lowest energy points along the seams of surface intersections have been located in both the Franck-Condon region and the N-N dissociation pathway in the S, state. Once the system populates the S, state, in the viewpoint of energy, the radiationless decay via S-1/S-0(3) conical intersection followed by the N-N bond fission in the ground-state is more favorable in comparison with the N-N dissociation process in the S-1 state. A three-surface crossing region (S-1/T-1/T-2), where the S-1, T-1, and T-2 states intersect, was also found. However, the intersystem crossing process via S-1/T-1/T-2 is not energetically competitive with the internal conversion via S-1/S-0(3).

• 出版日期2008-9-25
• 单位吉林大学