Theoretical study of low-lying electronic states of OsO＋

As an important reactant and intermediate species in catalytic reactions, the ground state of OsO＋ has not been thoroughly studied until now, and the spectral properties of the low-lying states of OsO＋ are still lacking. In this work, high-level ab initio calculations are carried out using the recently developed SDSPT2+Q method to construct the potential energy curves (PECs) of low-lying Λ-S and Ω states of OsO＋, and the spectroscopic constants are obtained from the PECs. It is found that the ground state of OsO＋ is 4Π in the absence of spin–orbit coupling (SOC) and becomes Ω=5/2 after SOC being considered. Our results can help in the interpretation of catalytic mechanism involving OsO＋ and assignment of the photoelectron spectrum of neutral OsO.