Reactive molecular dynamics simulation for isotope exchange reactions in H/D systems: ReaxFFHD development

We developed the ReaxFFHD force field for the H2/D2 isotope exchange reactions. To the best of our knowledge, the ReaxFFCHO force field has not used to the isotope exchange reactions. Quantum calculations for the isotope exchange reactions are very massive and there are a few ab initio information for these reactions. The ReaxFFHD force field was developed by using experimental and computational results on both the concentration and the structural characteristics of all products in the H2/D2 isotope exchange process. In this work, we developed the reactive molecular dynamics (RMD) simulations for the reactionH2  D2 2HD in an electric field. The parameters are modified in such a way that the results are consistent with the previous results. The ReaxFFHD can predict the reaction of H2 and D2 at different temperatures and concentrations under an external electric field. We find out that in the reaction between H2 and D2 in a discharge chamber the production of three atomic molecules at lower temperatures is more favorable. The simulation results show that at low pressure, the production of H2D and D2H is very unlikely. By RMD simulations on a few H2/D2 systems, it was found that three atomic molecules are produced by consuming the diatomic molecules. The configuration of the produced three atomic molecules is triangular at all temperatures and concentrations.