激发态1，2-二硫环丁烯去活性和异构化机理的理论研究

运用完全活性空间多组态CASSCF方法研究了激发态1，2-二硫环丁烯（1,2-Dithiete）势能面交叉机理．自旋．轨道耦合（SOC）常数采用完全Pauli-Breit旋轨耦合算符（包括单电子和双电子项）进行计算，其强度为198．37或211．35cm^-1，对不同自旋态跃迂起着重要作用．研究结果表明：光激发1，3-dithiol-2-one导致形成主要产物trans—dithioglyoxal（Trans-MinS0）和次级产物thiolthioketene．计算与实验观察结果一致．

Theoretical study of deactivation and isomerization pathways of 1, 2-dithiete in excited electronic states

The potential energy surface crossings for 1,2-dithiete have been investigated using the complete active space self-consistent field （CASSCF） method. Using the full Pauli-Breit spin-orbit coupling （SOC） operator （HSO）, that consists of the one-electron （HSO1） and two-electron （HSO2） terms, we estimated the strengths of the SOC （198.37 when symmetry is imposed, and 211.35 cm^-1 with no symmetry constraints）, which plays an essential role in the spin transitions between different spin states. The calculations showed that the photolysis of 1,3-dithiol-2-one leads to the formation of trans-dithioglyoxal （Trans-MinSo） as a primary product which subsequently gives a secondary product identified as thiolthioketene. Our calculated results are in good agreement with experimental observations.