NaCCH自由基低能电子态的理论研究
Study on the low-lying electronic states of NaCCH radical

摘 要：采用CASSCF / CASPT2方法研究了NaCCH自由基的低能电子态，在C2v对称性下给出了NaCCH自由基9个低能激发态的几何、组态、CI系数、振子强度、垂直激发能和绝热激发能.研究结果表明，NaCCH自由基的基态X1Σ+几何和转动系数与实验值是一致的；谐振频率与其他理论方法得到的值也符合的很好；HOMO和LUMO轨道的能量间隔为3.80eV，对应着13Σ+的绝热激发能；除13Π外，其它低能激发态均是稳定状态；基态到三重态是自旋禁阻的.
Abstract: The CASSCF/CASPT2 methods are used to study the low-lying electronic states of the NaCCH radical. For the nine excited states of the NaCCH radical, the geometrical parameters, electron configurations, oscillator strengths, harmonic vibrational frequencies and excitation energies are calculated on the C2v symmetry. The results show that, for the ground state X1Σ+, the geometrical parameters and rotation coefficient are in agreement with other experimental reports, and the calculated harmonic vibrational modes are similar to other theoretical ones. Moreover, the HOMO and LUMO energy gap is 3.80 eV, which corresponds to the adiabatic excitation energy of the state 13Σ+. In addition to the state 13Π, the other low-lying excited states are stable states, and the transition from the ground state to the triplet states is spin-forbidden one.