Atomistic simulation of radiation effects in carbon-based materials and nitrides

Molecular dynamics computer simulations have proven to be an extremely useful method to examine the basic mechanisms of ion-induced damage production in materials. In the particular case of insulators with a high degree of ionic bonding, there are some complications in the simulations associated with how the charges on atoms should be handled. In this article I will review different approaches of handling the ionicity and discuss the limits of their applicability. I will also present some of our recent simulation results in GaN and hydrogenated amorphous carbon. Comparison of defect production in collision cascades in GaN simulated with two different models, one with explicit ionic interactions and another without, gives the surprising result that the primary damage production does not seem to be affected by explicit ionic interactions. This indicates that at least in GaN it is justified to use fast short-range interaction models in simulations of the primary states of radiation damage. (C) 2003 Elsevier B.V. All rights reserved.