Reactions and Reaction Rate of Atmospheric SO2 and O3– (H2O)n Collisions via Molecular Dynamics Simulations

An Ab Initio Molecular Dynamics Study of the Hydrolysis Reaction of Sulfur Trioxide Catalyzed by a Formic Acid or Water Molecule

Ab initio molecular dynamics (AIMD) calculations have been performed to investigate the role of dynamical and steric effects in formic acid (FA) or H₂O-catalyzed gas phase hydrolysis of SO₃ to form sulfuric acid. This was done by colliding FA or H₂O with the SO₃-H₂O complex and the water dimer with the SO₃ molecule and analyzing the outcomes of 230 AIMD trajectories. Our calculations show that, within simulation times used, sulfuric acid is formed in 5% of FA collisions but is not produced when H₂O collides with the SO₃-H₂O complex or when the water dimer collides with the SO₃ molecule. We also find that FA collisions have about 2 times higher probability to form the prereactive complex than H₂O collisions. Moreover, our simulations show that the SO₃-H₂O-FA prereactive complex is more stable in time than the SO₃-H₂O-H₂O prereactive complex. These findings indicate that the FA-catalyzed mechanism is favored over the H₂O one when looking from the steric and dynamic effect point of view. Additionally, AIMD simulations starting from the optimized structure of the SO₃-H₂O-FA prereactive complex have been computed to qualitatively estimate the rate of the sulfuric acid formation. Collisional energy has been observed to promote sulfuric acid formation more effectively than thermal excitation.

On the gas-phase reaction between SO2 and O2−(H2O)0–3 clusters – an ab initio study

An ab initio study on the outcome of a collision between SO₂ and the O₂⁻(H₂O)_0–2 anion.

Resolving the anomalous infrared spectrum of the MeCN–HCl molecular cluster using ab Initio molecular dynamics

Molecular dynamics simulations reveal that the asymmetric peak seen in IR spectra of acetonitrile–HCl molecular complexes are due to high population of complexes with partially broken hydrogen bonds.