Abstract
AbstractThe ground state and 23 other low-lying singlet and triplet electronic states of the strontium mono-sulfide molecule SrS, in the 2s+1Λ± representation, have been examined by ab initio calculations using the computational chemistry software MOLPRO and the graphical user interface GABEDIT. The potential energy curves, in terms of the internuclear distance R, resulted from the complete active space self-consistent field (CASSCF) and multi-reference doubly and singly configuration interaction (MRDSCI) with Davidson correction (+Q) calculations. The permanent dipole moments (μ) and the spectroscopic constants (Te: the electronic energy with respect to the ground state, ωe: the harmonic frequency, Re: the equilibrium internuclear distance, Be: the rotational constant, De: the equilibrium dissociation energy) have been investigated. The results of this work are in good agreement with the results available in literature. Moreover, for the first time, it was possible to study 20 new singlet and triplet electronic states of SrS molecule.
Highlights
In many areas of chemistry, the compound SrS, as all metal sulfides, is of great importance regarding the nature of the metal-sulfur bond
The spectroscopic constants of few other electronic states have not been calculated since the minima of their potential energy curves exist near locations of crossing or avoided-crossing between two states
In order to study the effect of decreasing the core orbitals of the SrS molecule during the MRCI calculations, another multi-reference doubly and singly configuration interaction (MRDSCI) computational trial has been applied to 2 states of SrS by removing 1 of the closed-shell s orbitals from the core orbitals and the corresponding spectroscopic constants have been calculated (Table 1/b)
Summary
In many areas of chemistry, the compound SrS, as all metal sulfides, is of great importance regarding the nature of the metal-sulfur bond. The results were limited to 2 electronic states only, the ground state X1Σ+ and the first excited state (2)1Σ+ (Pianalto, Brazier, Obrien, & Bernath, 1988) Another experimental study, in 2001, allowed the recording of the bond length of SrS, for state X1Σ+, using millimeter/submillimeter-wave direct absorption methods (Halfen, Apponi, Thompsen, & Ziurys, 2001). In 2010, experimental recordings were done on 4 isotopes of strontium mono-sulfide and the spectroscopic constants of the ground state X1Σ+ were obtained (Etchison & Cooke, 2010). This molecule has been studied by Partridge et al using ab initio calculations. Out of the 24 low-lying electronic states that are demonstrated in the current work, 20 new electronic states are studied here for the first time
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