The 18 Λ–S states correlated to the lowest dissociation limit of SiTe were calculated by using a high-level multireference configuration interaction(MRCI) method, including scalar relativistic and spin–orbit coupling effects. Based on the calculated potential energy curves, the spectroscopic constants of bound states were determined, which are well consistent with previous experimental results. The spin–orbit matrix elements between the Λ–S states were computed, which lead to an in-depth understanding of perturbations on the electronic state a3Π. Finally, the transition dipole moments of allowed transitions A1Π–X1Σ+, E1Σ+–X1Σ+, a3Π–d3?, a3Π–a 3Σ+, a3Π–e3Σ-, and the radiative lifetimes of A1Π, E1Σ+, and a3Π were evaluated.
Carbon monosulfide molecular ion(CS+), which plays an important role in various research fields, has long been attracting much interest. Because of the unstable and transient nature of CS+, its electronic states have not been well investigated. In this paper, the electronic states of CS+are studied by employing the internally contracted multireference configuration interaction method, and taking into account relativistic effects(scalar plus spin–orbit coupling). The spin– orbit coupling effects are considered via the state-interacting method with the full Breit–Pauli Hamiltonian. The potential energy curves of 18 Λ–S states correlated with the two lowest dissociation limits of CS+molecular ion are calculated, and those of 10 lowest states generated from the 6 lowest Λ–S states are also worked out. The spectroscopic constants of the bound states are evaluated, and they are in good agreement with available experimental results and theoretical values. With the aid of analysis of Λ–S composition of states at different bond lengths, the avoided crossing phenomena in the electronic states of CS+are illuminated. Finally, the single ionization spectra of CS(X1Σ+) populating the CS+(X2Σ+1/2, A2Π3/2, A2Π1/2, and B2Σ+1/2) states are simulated. The vertical ionization potentials for X2Σ+1/2, A2Π3/2, A2Π1/2, and B2Σ+1/2 states are calculated to be 11.257, 12.787, 12.827, and 15.860 eV, respectively, which are accurate compared with previous experimental results, within an error margin of 0.08 eV^0.2 eV.
