FONO2低能激发态和光电子谱的理论研究

Theoretical Study on the Low-lying Electronic States and Ionization Spectra of Fluorine Nitrate

采用CASSCF方法和ANO-S基组计算了FONO2分子及其阳离子的低能激发态,并采用CASPT2方法进行能量校正.预测了在低能激发态时FONO2分子的几何结构发生了很大变化,从基态的平面构型转变为空间的几何构型.然而在阳离子中没有发生相似的几何构型改变.此外,在分子的基态几何构型下,设计并计算了相应阳离子的垂直离子势,对分子的光电子谱给出了详细的解释.

Using the complete active space self-consistent field （CASSCF） method with the atomic natural orbital（ANO） basis set, we studied the ground state and low-lying excited states of fluorine nitrate and its cation. The stable geometry of ground state was the planar structure with the Cs symmetry, but the stable structures of excited states were changed to the nonplanar structure. However, the similar change of the cation geometry was not observed. Furthermore, the vertical ionization potential of the fluorine nitrate molecular was studied on the basis of the optimized geometry of the ground state. Taking the dynamic correlation effects into account, we used the second-order perturbation（CASPT2） method to obtain more reliable energies. The assignment of the first two bands is in an excellent agreement with the experimental data and the theoretical results, but in the higher energy region, the different assignments were completed bass of the CASPT2 results.