Radiation damage in metals

Sputtering

Sputtering has previously been simulated using classical molecular dynamics, yet how the ionic dynamics are affected by charge transfer remains an open question. We have been using a time-dependent self-consistent tight-binding framework to find out more.

So far our work in this area has been validating that Ehrenfest dynamics is suitable for this problem, as together with all the challenges of running large-scale cascade simulations we must also ensure sensible answers are given when ions are ejected from the surface.


Testing the validity of the Ehrenfest approximation by looking at charges on the atoms using Coulombic self-consistency. As a toy problem a single ion is ejected from the surface with a kinetic energy of 1keV. Red atoms are positively charged, blue negative. The surface shows the Hartree potential.	A snapshot from a sputtering simulation containing 16k atoms. An 1keV ion has hit a < 111 > surface at normal incidence, creating a cascade of charged moving ions and ejecting several from the surface.