Molecular Dynamics Simulation of the Hydrogen Isotope Sputtering of Graphite

We used a molecular dynamics simulation with the modified Brenner reactive empirical bond order potential to investigate the erosion of a graphite surface due to the incidence of hydrogen, deuterium, and tritium atoms. Incident particles cause pressure on the graphite surface, and the chemical bond between graphene layers then generates heat to erode the graphite surface. We evaluated the speed of surface destruction by calculating the pseudo–radial distribution function. The speed of surface destruction due to incident hydrogen isotopes was higher than that due to hydrogen atoms. The surface destruction increased exponentially and its decay time constant was a power function of the incident energy. We measured the erosion yield, which indicated a steady state for the graphite erosion. The erosion yield flux in the steady state increased linearly with the incident energy. The erosion yield flux was almost independent of the type of incident particle, and the erosion yield start time was smaller for hydrogen isotopes than for hydrogen atoms.