Extensive theoretical study on various low-lying electronic states of silicon monochloride cation including spin-orbit coupling.

The potential energy curves of the 23 Omega states generated from the 12 valence Lambda-S states of silicon monochloride cation are calculated for the first time using the internally contracted multireference configuration interaction method with the Davidson correction and entirely uncontracted cc-pV5Z basis set. Spin-orbit coupling is taken into account by the state interaction approach with the full Breit-Pauli Hamiltonian. Very good agreement is achieved between our computed spectroscopic properties and the available experimental data. In particular, the adiabatic excitation energies of the a3Pi(0+) and a3Pi(1) states computed by us are 31,708 and 31,830 cm(-1), respectively, in excellent agreement with the respective experimental values of 31,721 +/- 2 and 31,836 +/- 3 cm(-1). The curve crossings and the predissociation mechanism are investigated. The transition dipole moments are analyzed and the transition properties of the a3Pi(0+)-X1Sigma(0+)+ and a3Pi(1)-X1Sigma(0+)+ transitions are predicted, including the Franck-Condon factors and the radiative lifetimes.