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Abstract: The CASPT2 potential energy curves for S-loss dissociation from the X2Πg, A2Πu, , , 14Σ−, 14Π, 12Σ−, and 24Σ− states of the ion were calculated. A conical intersection point between the and potential energy surfaces was found. At the CASSCF level we located the minimum energy crossing points (MECPs) for the X2Πg/14Σ−, A2Πu/14Σ−, /14Σ−, /14Σ−, A2Πu/12Σ−, and /12Σ− state-pairs and calculated spin–orbit coupling values. MECP for the /12Σ− state-pair was not found. We suggest photodissociation processes via A2Πu and . Photodissociation mechanisms via A2Πu, , and proposed in the previous experimental studies are discussed. [Copyright &y& Elsevier]

Abstract: The 12Π(X2Π), 22Π, 12Σ+, 32Π, 42Π, and 22Σ+ states of the OCS+ ion were studied using the CASSCF and CASPT2 methods with a contracted ANO basis and 32Π and 42Π are characterized as shake-up ionization states. The CASSCF frequency calculations indicate that the 12Π, 22Π, 12Σ+, and 22Σ+ primary ionization states represent minima in the potential energy surfaces (PESs), and accurate CASPT2 adiabatic excitation energy (T 0) calculations support assignments of the A, B, and C states to 22Π, 12Σ+, and 22Σ+, respectively. The CASSCF frequency calculations indicate that 32Π and 42Π represent saddle points in the PESs. We found minima in the PESs of the 52A′ and 42A″ states (related to 42Π), and the CASPT2 T 0 values for 52A′ and 42A″ are between the T 0 values of B2Σ+ and C 2Σ+. The observed satellite bands between the B and C bands in spectrum can be (partially) attributed to 52A′ and 42A″. [Copyright &y& Elsevier]