Molecular Dynamics Study of Gas-Surface Interaction. 2nd Report. Analysis on the Energy Distribution after the Collision and the Vibration of the Potential Energy Surface.

Abstract

The scattering of an oxygen gas molecule from a clean graphite surface is simulated using the molecular dynamics method. According to our previous report, the numerical simulation has shown quantitative agreement with experimental results, indicating that the method can simulate the trajectory of a scattering gas molecule with high accuracy. Here, the translational and rotational energy distribution after the first collision is analyzed. The translational energy distribution is fitted to a gaussian distribution. The parameters obtained by the fitting process obey the model equation that was obtained by assuming that the gas-surface collision is an ellipse hitting a hard-cube. The rotational energy distribution is fitted to the Boltzmann distribution and the non-Boltzmann distribution. The parameters for rotation also obey the model equation. Also, the vibration of the potential energy surface was analyzed and it was found that the amplitude can be defined as a function of surface temperature.