Computational Studies on Reaction Dynamics of Atmospheric Molecules

Abstract

Predicting environmental chemical changes requires an understanding of the reaction kinetics of air molecules. The rate constants, activation energies, and reaction mechanisms of important atmospheric processes are investigated in this study using computational chemistry approaches. Potential energy surfaces (PES) and transition states were calculated by quantum mechanical calculations utilising Density Functional Theory (DFT) and Coupled Cluster (CCSD(T) techniques. To further assess their thermodynamic sensitivity, we calculated reaction rate constants over a range of temperatures using Transition State Theory (TST). To better understand transient molecular interactions, MD simulations were conducted using ReaxFF force fields. There was a high degree of agreement, within a reasonable range of error, between the calculated rate constants and experimental data from NASA and NIST databases. These results show that computational methods work well for atmospheric chemistry studies, even when it's hard to get good experimental observations.