Potential energy curves, spectroscopic constants, and vibrational energy levels of CS⁺(X²Σ⁺/A²Π)

ABSTRACT

The accurate potential energy curves (PECs) of the ${\mathrm{C}\mathrm{S}}^{+}\left(X^2{\mathrm{\Sigma }}^{+}/A^2\mathrm{\Pi }\right)$ are obtained based on the ab initio energies which are calculated via the multi-reference configuration interaction including the Davidson correction method (MRCI(Q)), together with aug-cc-pVXZ (X = T, Q, 5, 6) basis sets. The ab initio energy points calculated by the MRCI(Q)/aug-cc-pVXZ (X = Q, 5) are subsequently extrapolated to the complete basis set (CBS) limit. For the ground state of $\mathrm{C}{\mathrm{S}}^{+}$, it is found that there is a lower barrier in the long range, and the Gaussian function can be used to fit it. Then the root mean square derivations, spectroscopic constants, vibrational energy levels and classical turning points are obtained based on such obtained analytical potential energy functions (APEFs). The present results are in agreement well with other theoretical and experimental works, which prove that such APEFs including Gaussian function are reliable and highly accurate in both short and long ranges.

GRAPHICAL ABSTRACT

KEYWORDS:

• Potential energy curves
• spectroscopic constants
• complete basis set (CBS)
• analytical potential energy functions

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (Grant Nos. 11674198, and 11874241).