Accurate ab initio potential energy curves and spectroscopic properties of the low-lying electronic states of OH⁻ and SH⁻ molecular anions

ABSTRACT

Multireference configuration interaction method was used in order to generate accurate potential energy curves of the OH, SH, OH⁻ and SH⁻ electronic states correlating to the three lowest dissociation limits. These curves were used in addition with core–valence correlation and scalar relativistic corrections for the calculations of accurate spectroscopic constants of bound states, which generally are found in excellent agreement with best available experimental and theoretical values in the literature. The spin–orbit interactions between electronic states have been calculated for the cases in which the couplings were assumed to be responsible for perturbations and used to explain the predissociation of A²Σ⁺ state of OH and SH by dissociative states 1⁴Σ⁻, 1²Σ⁻ and 1 ⁴Π. Dipole moment functions were also computed along internuclear distances and used to explain polarity of these molecules in different calculated electronic states. In addition, stability and metastability of electronic states (X ¹Σ⁺, A¹Π and a³Π) of OH⁻ and SH⁻ molecular anions have been studied relatively to curves of neutral parent electronic states. Finally, we have computed adiabatic electron affinity of OH and SH and these values have been found in very good agreement with the best experimental values and resort as among the best achieved values.

KEYWORDS:

• OH
• SH
• spectroscopic constants
• stability
• metastability
• spin–orbit coupling
• dipole moment

Acknowledgments

The authors are grateful to LSAMA TEAM (Faculty of Science, University of Tunis El Manar, Tunis (Tunisia)) for valuable discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.