PARAMETRIC STUDY OF SIMULATION PARAMETERS FOR MOLECULAR DYNAMICS MODELING OF REACTIVE CARBON GASES USING REAXFF

摘要

Carbon-based materials are ideal for structural aerospace components because of their high specific strength and high specific stiffness relative to traditional aerospace metallic materials. Reactive carbon-based gases are common in the synthesis of carbon-based materials. Various reactive gas processes occur in the production of carbon-based material constituents like nanotubes, amorphous carbon films, and even soot particles formed from combustion. Electron beam deposition [1], chemical vapor deposition [2, 3], pulsed arc discharge deposition [4], plasma deposition [5-8], pulsed laser deposition [9, 10], laser ablation, combustion [11, 12], and ion beam irradiation [13] are all processes that are used in the manufacture of carbon-based materials where the source of carbon is a reactive carbon-based gas. Because of the wide range of processing methods and conditions that can be used to fabricate carbon-based materials, their development can be time-consuming and expensive. Molecular modeling can be used to greatly facilitate the development and design of carbon-based materials. Molecular models give detailed atomic information not easily obtained from physical samples, and they provide precise control over environmental variables in the simulation. Traditionally, researchers modeled atom-atom interactions using Molecular Dynamics (MD) with fixed-topology force fields where bonds are defined at the beginning of a simulation and remain fixed throughout the simulation. However, since bond dissociation and formation are critical steps in the formation of carbon-based materials from a reactive gas, a new generation of force fields, such as the recently-developed Reax Force Field [14] (ReaxFF), are required to simulate these material systems. The ReaxFF has the capacity to model bond dissociation and formation in carbon-based materials.