Connection between the Upper and Lower Energy Regions of the Potential Energy Surface of the Ground Electronic State of the HSO2 System

Reactivity properties of the HOSO and HSO2 isomers in liquid medium: a sequential Monte Carlo/quantum mechanics study

CONTEXT

The rationalization of acid rain formation steps is fundamental for mitigating its effects. It is believed the hydroxysulfinyl radical is an intermediate species for the production of atmospheric sulfuric acid. Two stable configurations HOSO and HSO₂ have been reported for such a radical in the gas phase. This work aims at studying these isomers in the aqueous medium. The electrical and reactivity quantities - electronic chemical potential ([Formula: see text]), chemical hardness ([Formula: see text]), and electrophilicity ([Formula: see text]) - are here calculated and compared. Considering first solvation shells (15 H₂O for HSO₂ and 23 H₂O for HOSO), an increase of 25% in the dipole moment of HSO₂ was obtained, while the dipole moment of HOSO decreases in 11%. Both solvated isomers grow softer ([Formula: see text] decreases) contrasted to the gas phase.

METHODS

HOSO and HSO₂ are studied through a sequential Monte Carlo/quantum mechanics approach. Lennard-Jones plus the Coulomb potentials were used to represent intermolecular potential interaction in the frame of the DICE package. Molecular structure calculations were performed at CASPT2/aug - cc - pV(T + d)Z level of theory using the MOLPRO suite of programs.

An accurate full-dimensional potential energy surface for the reaction OH + SO → H + SO2

An accurate full-dimensional PES for the OH + SO ↔ H + SO₂ reaction is developed by the permutation invariant polynomial-neural network approach.

A quasi-classical trajectory study of the OH + SO reaction: the role of ro-vibrational energy

The reaction cross section and the reaction probability after forming the complex as a function of vibrational energy of reactants.