C6H5N光谱性质的多组态二级微扰理论研究

采用全活化空间自洽场方法(CASSCF)在C2v对称性和6-31g(d,p) 基组水平下, 研究了C6H5N自由基及其阴阳离子的基态和低激发态性质. 为了进一步考察动态电子相关效应, 采用多组态二级微扰理论(CASPT2)获得更加精确的能量值. 计算得到13A2→13A1和13A2→13B2在4303.1和4212.2 kJ/mol处的激发可分别归因于π(b1)→ny和π(a2)→ny的跃迁, 而13A2→13B1和13A2→11B1在2634.9和2700.4 kJ/mol处的激发具有nx→π*(a2)和π(a2)→nx的混合跃迁特征, 理论波长与紫外吸收光谱得到的实验数据一致. 计算得到的电离能与实验值也非常接近.

Studies on Spectroscopy Character of C6H5N Using Multiconfiguration Second-Order Perturbation Theory

Complete active space self-consistent field(CASSCF) calculations with 6-31g(d,p) basis sets were performed for a dozen of electronic states of nitrate free radical, C6H5N, and its positive and negative ions in C2v symmetry. All calculated states were valence states and their characters were discussed in detail. For all the calculated states, the accuracy of the total energies was improved by including dynamic electron correlation via the multiconfiguration second-order perturbation theory(CASPT2) method. The results suggest that the calculated transitions of 13A2→13A1 and 13A2→13B2 at 4303.1 and 4212.2 kJ/mol are attributed to π(b1)→ny and π(a2)→ny transition, respectively, while those of 13A2→13B1 and 13A2→11B1 at 2634.9 and 2700.4 kJ/mol belong to the mixture of nx→π*(a2) and π(a2)→nx transitions. The ionization energies were obtained in comparison with the photoelectron spectrum(PES) data. These above results are in agreement with the previous experimental data, which is discussed in detail.