H2S 和H2S+的振动光谱和电子能谱计算.

The potential energy surfaces and photoelectron spectra of the interstellar molecule H2S and its cation H2S+ were calculated using ab initio methods based on the MOLPRO software package. First, the potential energy surfaces of H2S expanded along the normal coordinates were obtained at the（U）CCSD/cc-pVQZ level of theory. The potential energy surfaces visually describe the effect of different vibrational modes coupling on the molecular energy change, and the combined effect of the asymmetric stretching vibration of the S-H bond and the in-plane bending vibration makes the potential energy change range of the system significantly larger. The vibrational multi-reference configuration interaction method was used to calculate the anharmonic vibrational frequencies and vibrational spectrum, and the calculations showed that strong Fermi resonances appear between the overtones and combination bands, resulting in a significant enhancement of the infrared intensity at the corresponding bands. Finally, the photoelectron spectrum of H2S X¹A1→ H2S+ X²B1 was calculated for the first time using the Raman wave function and the contracted invariant Krylov subspaces method. This study will help to further understand the internal structure of interstellar molecules and provide a reference for experimental studies and interstellar observations. [ABSTRACT FROM AUTHOR]