Generation of an amorphous graphite substrate by cumulative deuterium bombardment using molecular dynamics with full nonbonded interactions

A deuterated amorphous carbon target is generated from a fresh graphite layer via hyperthermal irradiation with deuterium ions using molecular dynamics (MD) simulations. We use interatomic potentials that include nonbonded (long-range) interactions for maximum accuracy and simulate cumulative bombardment up to doses of 5.80 x 1016 ions cm-2 at 1000 K. The graphite target goes through several stages of erosion and swelling, leading to complete amorphization and significant density loss. The calculations show a transition from graphitelike hybridization to a mixture of diamondlike and linear hybridizations with dose. It is concluded that the current sample sizes obtained directly by cumulative irradiation affordable with MD are not sufficiently large to be used for sputtering calculations under steady-state conditions.