Density functional theory study of CeD$_{\mathrm{x}}$ with application to ejecta break-up in reactive gases

When ejecta are produced in a reactive gas, the diffusion of the reacting gas into the ejecta particles may have an important effect on break-up. This can influence the rate of break-up, particle size, and composition. In this study, density functional theory calculations were performed to explore the properties of CeD$_{\mathrm{x}}$in support of experiments of Ce ejected into Dgas. Under these conditions, the diffusion of D into Ce ejecta is of fundamental importance to the ejecta physics. We perform quantum molecular dynamics simulations to derive fundamental quantities including temperature dependent diffusion coefficients, $x$dependent heat capacity, and reflectivity. Our results are interpreted in terms of relative phase composition of ejecta and discussed in application to experiments.