AB INITIO MOLECULAR DYNAMICS SIMULATIONS ON HIGH-TEMPERATURE REACTION RATES OF POTASSIUM OXIDES

摘要

In this paper, we present a new approach for calculating chemical reaction rates based on molecular collision theory, in which molecular collision cross sections are calculated by averaging over all reactive trajectories from ab initio molecular dynamics simulations. The molecular collision radius is determined by both the reactive and non-reactive trajectories of molecular dynamics under constant temperature. Thus, both steric and temperature effects have been take into account for the molecular collision cross sections. We have applied this approach to calculate the reaction rates of reactions KO + CO = K + CO_2, KO + C = K + CO, and K_2O + CO_2 = K_2CO_3 under high temperature. A comparison with other theories shows that the results are reasonably accurate. It also shows that under higher temperature the probabilities of successful reaction resulting from particle collision are low because the products are not stable.