Ab initio study of the lowest , and states of the SiN+ cation

Abstract

Abstract The equilibrium bond lengths, harmonic frequencies, first-order anharmonicity constants, rotational constants, centrifugal distortion constants, and rotation–vibrational constants, as well as the dipole moments, excitation and dissociation energies for the lowest 3 Σ − , 3 Π and 1 Σ + states of SiN + have been calculated using CASSCF, CMRCI, CCSD(T) and density functional (B3LYP and B3PW91) theories combined with Dunning's correlation-consistent basis sets. Core-correlation effects have also been included in order to obtain a satisfactory accuracy for the spectroscopic constants. Our calculations strongly support 3 Σ − as the ground state; the 3 Π state lies only 460 cm −1 above the 3 Σ − state, while the 1 Σ + state lies 6865 cm −1 above the ground state. Our DFT calculations on the triplet surface of SiN + converge to the 3 Π state which is clearly not the ground state.