The Renner Effect in the X̃ ²A″ and à ²A′ Electronic States of HSO/HOS

Abstract

We report a theoretical investigation of the X (2)A" and à (2)A' electronic states of HSO/HOS. Three-dimensional potential energy surfaces for the X (2)A" and à (2)A' electronic states of HSO/HOS have been calculated ab initio by the core-valence MR-SDCI+Q/[aug-cc-pCVQZ(S,O),aug-cc-pVQZ(H)] method, and near-global potential energy surfaces have been constructed. These surfaces have been used, in conjunction with our computer program DR, for calculating HSO/HOS rovibronic energies in the electronic states X (2)A" and à (2)A'. Both electronic states have nonlinear equilibrium geometries and they correlate with (2)Π states at the H-S-O and H-O-S linear configurations so that they exhibit the double Renner effect. The present DR calculation of the rovibronic energies for the X (2)A" and à (2)A' electronic states of HSO/HOS is complicated by the Renner-interaction breakdown of the Born-Oppenheimer approximation and by HSO/HOS isomerization. Calculated energies are reported together with analyses of the rovibronic wave functions for selected states. These analyses explore the interplay between the effects of, on one hand, Renner interaction and, on the other hand, isomerization tunneling in the rovibronic dynamics of HSO/HOS.

On the Detectability of the HSS, HSO, and HOS Radicals in the Interstellar Medium

“…Additionally, the n 2 bending frequency computed here to be 1013.9 cm −1 is 2.9 cm −1 above the experimental result of 1011 cm −1 (Yoshikawa et al 2009) and an improvement over a recently computed value using a near-global PES (Ovsyannikov et al 2013). The n 3 S-O stretch, on the other hand, is off from experiment (1084 cm −1 ) here by 13.4 cm −1 , while the previous PES is much closer to experiment at 1087.79 cm −1 .…”

“…The n 3 S-O stretch, on the other hand, is off from experiment (1084 cm −1 ) here by 13.4 cm −1 , while the previous PES is much closer to experiment at 1087.79 cm −1 . However, the most intense of the fundamental vibrational frequencies will be the H-S stretch at 2335.7 cm −1 which is nearly 80 cm −1 less than that computed previously (Ovsyannikov et al 2013). No previously computed CcCR fundamental vibrational frequencies have ever produced errors of this magnitude, leading us to put forth that the H-S stretch is at a lower frequency than was previously believed.…”

“…Finally, HSO isomerizes to HOS preferentially when compared to hydride dissociation (Martinez-Nunez et al 2002), and is known to be 4.2 kcal mol −1 lower in energy than HOS (Wilson & Dunning 2004). As a result, if HSO has any abundance in the ISM, HOS likely will, as well, and its spectroscopic values can be refined beyond those available in the current literature (Denis 2009;Ovsyannikov et al 2013). …”

Theoretical Investigation on Electronic Excited States of the HSO Radical

“…Our optimized geometries of the ground states (X 2 A″) calculated by icMRCI with the CBS basis set are between the two available experimental measurements. , The deviations are about 0.024 Å, 0.001 Å, and 1.7° for R S–O , R S–H , and ∠H–S–O, respectively, while for harmonic vibrational frequencies, less than 8, 6, and 25 cm –1 for the low-frequency stretching mode ω 1 , the bending mode ω 2 , and the high-frequency stretching mode ω 3 , respectively. Compared with the latest calculated results considering the Renner effect, the theoretical values obtained here (1.359 Å, 1.494 Å, and 104.9°) are in good agreement with the results (1.365 Å, 1.495 Å, and 104.9°), with the difference only about 0.006 and 0.001 Å in bond lengths . For the first excited doublet state, the geometrical parameters are 1.652 Å, 1.343 Å, and 93.7° corresponding to R S–O , R S–H , and ∠H–S–O, respectively, which are consistent with the experimental data R S–O = 1.661 Å, R S–H = 1.342 Å, and ∠H–S–O = 95.7° .…”

“…Investigation on the structure, spectrum, and dynamics of the electronic states of the HSO radical is thus of pivotal importance to understand the reactions and photochemical processes involving sulfur-containing species, which has attracted many experimental ,− and theoretical − studies during the past decades. The first theoretical study could be dated back to over 35 years ago by Sannigrahi et al, in which the geometries of the electronic ground state and the first excited state were predicted. , Several high-level ab initio calculations have been performed since then, focusing on the low-lying electronic states of the HSO radical. ,, Experimentally, the transition between the electronic ground state 2 A″ and the excited state 2 A′ for HSO was first reported by Schurath et al Later, Kakimoto et al and Ohashi et al studied the vibronic spectra of the HSO and DSO radicals via Doppler-limited laser excitation spectroscopy to determine accurate molecular constants of the ground and the excited states.…”