Invitada: Atomistic simulations of swift ion bombardment

E.M. BRINGA

Valparaíso

Congreso; V Encuentro Sudamericano de Colisiones Inelásticas; 2010

Universidad Técnica Federico Santa Maria

Atomistic simulations are often used to study the bombardment of ions in the regime where elastic collisions dominate, but they rarely model bombardment when electronic effects dominate energy deposition in the target. There are several models to include these electronic effects within classic molecular dynamics (MD) simulations like Coulomb explosions, “thermal spikes”, and etcetera. MD simulations follow the evolution of a system of atoms interacting trough some empirical potential. Using current parallel computers millions of atoms can be followed during tens of picoseconds. Such systems are large enough and can be studied long enough to account for the early stages of radiation damage. Later stages have to be studied with other techniques, like kinetic Monte Carlo or rate theory. Ion tracks [1], surface craters [2] or hillocks, electronic sputtering [3], and other radiation damage indicators can be predicted in this way. Examples from materials science, surface physics, and astrophysics will be shown to illustrate that these models are relatively simple, but provide a reasonable description of experimental results when electronic stopping power cannot be neglected. Future directions to describe electronic effects in atomistic simulations will also be discussed. This work has been carried out in collaboration with several people, including D. Schwen, D. Farkas, J. Monk, A. Caro, J. Rodriguez-Nieva, T. Cassidy, R.E. Johnson, R. Papaléo, M. Da Silva, C. Ruestes, and Nestor Arista. Figure 1. MD simulation of hillocks in tetrahedral amorphous carbon, showing increasing hillock height with increasing electronic stopping [4]. References [1] R. Devanathana, P. Durhamb, J. Dua, L.R. Corrales and E.M. Bringa, Nuclear Instruments and Methods in Physics Research Section B 255, 172 (2007). [2] E.M. Bringa, R.E. Johnson, R. M. Papaléo, Phys. Rev. B 65, 094113 (2002). [3] E.M. Bringa and R.E. Johnson, Phys. Rev. Lett. 88, 165501 (2002). [4] D. Schwen and E.M. Bringa, submitted (2010).