Ab initio study of the ground and excited electronic states of the SiNa⁺ molecular ion

Abstract

Potential energy curves for the 1,3 Σ + , 1,3 Π, and 1,3 Δ electronic states of SiNa⁺ system were computed using high-level quantum chemical methods, including RHF, SA-CASSCF, and configuration interaction (CI) with the Pople and Davidson corrections. These calculations were performed in combination with augmented correlation-consistent basis sets (aug-cc-pVnZ, with n=Q, 5). To improve accuracy, basis set superposition errors were corrected using the counterpoise method results and were extrapolated to the complete basis set (CBS) limit.Additionally, we determined the permanent dipole moments, transition dipole moments, vibrational energy level spacings and radiative life time. Furthermore, the polarizability of the Si atom was evaluated using a long-range fit, the WKB semiclassical approximation, and several quantum chemical methods, including HF, MP4, CCSD(T), CI, and MRCI, yielding results that are in good agreement with existing theoretical and experimental data.