Theoretical Study On Electronic State Structure And Photodissociation Of Hydrogen Disulfide

As the smallest disulfide molecule,hydrogen disulfide has important research value in many fields such as biochemistry,chemical combustion,atmospheric chemistry,and interstellar medium.Our knowledge about the electronic state structure and dynamics of hydrogen disulfide molecules is of great significance to understand the spectroscopy and chemical reaction process.In this paper,we perform a high-level ab initio calculations on the electronic state structure of hydrogen disulfide molecules and photodissociation in the ultraviolet region.The main results are summarized in the following:Using the internally contracted multireference configuration interaction?icMRCI?method,we calculate the vertical excitation energy,oscillator strength,main configuration and electronic transition of the 13 electronic states of HS₂ molecules with energy less than 8 eV.The geometric structure and vibrational frequencies of X²A'',A²A',2²A''are obtained.The potential energy curves of all the 13 states are calculated along the HSS bond angle,the HS bond length and the SS bond length.Based on the spin-orbit coupling matrix element and the non-adiabatic coupling matrix element,we analyze the interaction between high-electron excited states.Our results indicate the photodissociation mechanism of HS₂ molecules in the ultraviolet region,that is,the HS₂molecule is excited to the 2²A"state,and dissociates along the HS?²??+S?³P?or H?²S?+S₂?¹?_g?channel through non-adiabatic coupling with 3²A"The strong SOC effect between 2²A'?or 1⁴A"?dissociates and reaches the HS?²??+S?³P?channel.Using the multi-reference configuration interaction method?MRCI?and coupled-cluster with the noniterative triples corrections F12?CCSD?T?-F12?method,we calculate the spectral constants of the ground state of the H₂S₂⁺isomers.For the trans-H₂S₂⁺molecule,which has the lowest energy of the isomers,we calculate the oscillator strength and transitions of twelve electronic states with a vertical excitation energy up to 8.43 eV using the icMRCI+Q method.Our research would help to understand the electronic excited state characteristics of H₂S₂⁺molecules,and stimulate further research on the interaction and dynamics of high-electron excited states.