H_2CCC光谱性质的从头算研究

ab initio Study on the Spectroscopy of H_2CCC

采用全活化空间自洽场方法(CASSCF)在C2v对称性和ANO-S基组水平下,研究了H2CCC自由基及其阴阳离子的基态和低激发态性质.为了进一步考虑动态电子相关效应,采用多组态二级微扰理论(CASPT2)获得了更加精确的能量值.计算得到X1A1→1A2,X1A1→1B1和X1A1→21A1在159.0,216.5和476.4kJ/mol处的激发可分别归因于π(b2)→π*(b1),n(a1)→π*(b1)和π(b1)→π*(b1)的跃迁,理论波长与紫外吸收光谱得到的实验数据一致.计算得到的电子亲和势与实验值也非常接近.

Complete active space self-consistent field（CASSCF） calculations with ANO-S basis sets were performed for a few electronic states of propadienylidene, H2CCC, and its cation and anion in C2π symmetry. For all the calculated states, the accuracy of the total energies was improved by including dynamic electron correlation via the muhiconfiguration second-order perturbation theory（CASPT2） method. The results suggest that the calculated transitions of X1A→1A2,X1A1→B1and X1A1→21A1 at 159.0,216.5and 476.4kJ/mol are attributed to π（b2）→π（b1）,n（α1）→π（b1） and π（b1）→π＋（b1） transition, respectively. The electron affinities were obtained in comparison with the photoelectron spectrum（PES） data. These above results are in agreement with the previous experimental data.