Vibrational spectra and photoelectron spectra calculations of H2S and H2S+
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 ener-gy 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 fre-quencies 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 corre-sponding 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 fur-ther understand the internal structure of interstellar molecules and provide a reference for experimental studies and interstellar observations.
Potential energy surfaceVMRCIVibrational spectroscopyPhotoelectron spectroscopy
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