Connectivity-Based Parallel Replica Dynamics for Chemically Reactive Systems: From Femtoseconds to Microseconds

KL Joshi and S Raman and ACT van Duin, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 4, 3792-3797 (2013).

DOI: 10.1021/jz4019223

Reactive force field methods such as AIREBO, ReaxFF and COMB, are extremely useful for studying physical and chemical interactions between molecules and materials. However, many chemical reactions have relatively high activation energies, putting them beyond the times-scale of conventional molecular dynamics (MD) at modest temperatures. To capture the low-temperature long-lived radical chemistry in atomistic simulations, we have developed a new transition detection scheme for performing Reactive Parallel Replica Dynamics (RPRD) simulation enabling an extended MD time-scales, essentially up to a microsecond using ReaxFF. In the newly implemented event detection scheme, the transition events are identified whenever there is a change in connectivity of any atom. 1-Heptene pyrolysis is chosen as a model system, and RPRD simulations are performed at temperatures as low as 1350K for up to 1 mu s for a system consisting of 40 heptene molecules. The chemical mechanism and the product distribution that were obtained from the RPRD simulation are in reasonable agreement with shock tube experiments.

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