Double many-body expansion potential energy surface for ground state HSO2

Abstract

A global potential energy surface is reported for the ground electronic state of HSO2 by using the double many-body expansion (DMBE) method. It employs realistic DMBE functions previously reported from accurate ab initio calculations (in some cases, fine tuned to spectroscopic data) for the triatomic fragments, and four-body energy terms that were modelled by fitting novel ab initio FVCAS/AVTZ calculations for the tetratomic system. In some cases, FVCAS/AVDZ energies have been employed after being scaled to FVCAS/AVTZ ones. To assess the role of the dynamical correlation, exploratory single-point Rayleigh-Schrödinger perturbation calculations have also been conducted at one stationary point. All reported calculations are compared with previous ab initio results for the title system. The potential energy surface predicts HOSO to be the most stable configuration, in good agreement with other theoretical data available in the literature. In turn, the HSO2 isomer with H bonded to S is described as a local minimum, which is stable with respect to the H + SO2 dissociation asymptote.

A quasiclassical trajectory study of the OH+SO reaction: The role of rotational energy

“…Figure 1 presents a contour plot for reaction 1, according to HSO 2 DMBE PES. The same nomenclature used before 17 is applied here. Thus, HOSO stands for the global minimum with the hydrogen atom bonded to the oxygen, lying 71.8 kcal mol −1 below OH+ SO limit.…”

“…17 and references therein͒ and four-body energy terms to mimic ab initio CASPT2 / FVCAS/ AVXZ ͑X = D , T͒ calculations for the tetratomic system. Since such a potential function has already been described in detail elsewhere, 17 we focus on features which are of relevance for the title reaction. Figure 1 presents a contour plot for reaction 1, according to HSO 2 DMBE PES.…”

“…17 It employs realistic DMBE functions previously reported for the diatomic and triatomic fragments ͑see Ref. 17 and references therein͒ and four-body energy terms to mimic ab initio CASPT2 / FVCAS/ AVXZ ͑X = D , T͒ calculations for the tetratomic system.…”

“…17 It employs realistic DMBE functions previously reported for the diatomic and triatomic fragments ͑see Ref. 17 and references therein͒ and four-body energy terms to mimic ab initio CASPT2 / FVCAS/ AVXZ ͑X = D , T͒ calculations for the tetratomic system. Since such a potential function has already been described in detail elsewhere, 17 we focus on features which are of relevance for the title reaction.…”

“…by using the quasiclassical trajectory method 16 and a previously reported single-valued potential energy surface ͑PES͒ for the ground electronic state of HSO 2 , 17 aiming to investigate the effects of reactant's rotational energy. The paper is organized as follows: the next section gives a brief description of the properties of the PES, while the calculation methodology is presented in Sec.…”