Novel Algorithm in Simulation of Gas Molecule Collision in Equilibrium State

A novel algorithm was developed for molecular dynamics simulation of gas molecule collision in equilibrium state. The original work includes:i) the non-constant time step defined as the shortest free flight time; ii) the derivation of molecular collision criteria; iii) a realistic number of gas molecules; (iv) the scheme for updating 3D non-centroid collision velocity; and v) a self-developed simulation program in C-language. Collision of air molecules in two cubic boxes was simulated in the new algorithm and evaluated in molecular dynamics. The simulated and theoretically calculated statistical results, including but not limited to the numbers of molecule-molecule/molecule-wall collisions, distributions of velocity, free-path and free-flight time, were in good agreement and within probability fluctuation range. We suggest that the novel algorithm be of some basic and technological interest in understanding the microscopic mechanisms responsible for diffusion and/or migration of non-equilibrium gas-mixtures.