Study on spectroscopic parameters and molecular constants of CS+(X2Σ+) and CS+(A2Π) by MRCI

Abstract

The potential energy curves (PECs) of CS+(X2Σ+) and CS+(A2Π) have been investigated using the full valence complete active space self-consistent field (CASSCF) method through the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach over the internuclear separation range from 0.05 to 0.60 nm. In the present calculations, the basis sets for S and C are both aug-cc-pV6Z. The spectroscopic parameters of three main isotopes (12C32S+, 12C33S+, 12C34S+) have been determined. The present D0, De, Re, ωe, ωeχe, αe and Be for 12C32S+(X2Σ+) are 6.4694 eV, 6.5542 eV, 0.14975 nm, 1371.89 cm-1, 7.5746 cm-1, 0.006481 cm-1 and 0.8616 cm-1, respectively; and those for CS+(A2Π) are 4.8460 eV, 4.9084 eV, 0.16449 nm, 1009.31 cm-1, 6.4970 cm-1, 0.006110 cm-1 and 0.7134 cm-1, respectively, which have been compared with those of previous results reported in the literature. And the comparison shows that the present results and the experimental results are in excellent agreement with each other. With the PECs of CS+(X2Σ+) and CS+(A2Π) determined here, the vibrational states for each electronic state are determined when the rotational quantum number J equals zero (J = 0). For the first 30 vibrational states, the vibrational level G(υ), inertial rotation constant Bυ and centrifugal distortion constant Dυ for 12C32S+(X2Σ+) and 12C32S+(A2Π) are evaluated when J = 0, which are in good accordance with the available RKR data.