REACTER: A Heuristic Method for Reactive Molecular Dynamics

Abstract

REACTER is a heuristic protocol that allows complex, predefined reactions to be modeled in atomistic, fixed-valence molecular dynamics (MD) simulations. The method is applicable to a broad range of chemical reactions and permits much larger and longer reactive simulations than existing approaches. One or more competing multistep reactions or series of reactions can be invoked simultaneously. Special treatment can be applied to neighboring atoms to relax high-energy configurations while the simulation progresses. The original implementation of REACTER, which was included in the open-source LAMMPS simulation package as fix bond/react, was only available for serial simulations. This work describes the expansion of the REACTER protocol for use in parallel simulations, as well as the addition of various new options, including deletion of reaction byproducts, reversible reactions, and custom reaction constraints. The capability of the parallel implementation is demonstrated through large-scale simulations (200000+ atoms) of the polymerization of polystyrene and nylon-6,6. The morphologies of both polymers are analyzed after reaching >99% extent of polymerization. Finally, the newly added reversible reactions feature is demonstrated by rupturing these highly entangled systems under uniaxial strain by defining a chain scission reaction.

Solid with infused reactive liquid (SWIRL): A novel liquid-based separation approach for effective CO 2 capture

“…Chemical reactions were modeled using a simplified reaction method developed recently by Gissinger et al ( 48 , 49 ). The method is useful for known reaction pathways in which two atoms are bonded together once they get closer than a predefined distance.…”

Characterization of Cure Behavior in Epoxy Using Molecular Dynamics Simulation Compared with Dielectric Analysis and DSC

“…For crosslinking resin and hardener, the REACTER protocol [ 29 , 30 ] as implemented in LAMMPS was used. The cutoff distance D cut , which correlated to the bond energy, was defined as a criterion for bond breaking and creation.…”

Polymer Adhesion: Seeking New Solutions for an Old Problem

“…Even when using a reactive force field or a hybrid quantum chemical model, the cross-linking reaction cannot be simulated by “brute force” integration of the MD equations of motion because of the extreme disparity between the experimental and the computationally accessible time scales. Rather, the cross-linking reaction must be performed by a combination of probabilistic bond creation and structure relaxation steps. − Once this is done, a simulation of mechanical deformation with a reactive force field may describe also the ultimate mechanical properties …”