Electron-ion coupling effects on simulations of radiation damage in pyrochlore waste forms
AE Ismail and JA Greathouse and PS Crozier and SM Foiles, JOURNAL OF PHYSICS-CONDENSED MATTER, 22, 225405 (2010).
We have performed molecular dynamics simulations of cascade damage in the gadolinium pyrochlore Gd(2)Zr(2)O(7), comparing results obtained from traditional simulation methodologies that ignore the effect of electron-ion interactions with a 'two-temperature model' in which the electronic subsystem is modeled using a diffusion equation to determine the electronic temperature. We find that the electron-ion interaction friction coefficient gamma(p) is a significant parameter in determining the behavior of the system following the formation of the primary knock- on atom (PKA; here, a U(3+) ion). The mean final PKA displacement and the number of defect atoms formed is shown to decrease uniformly with increasing gamma(p); however, other properties, such as the final equilibrium temperature and the oxygen-oxygen radial distribution function, show a more complicated dependence on gamma(p).
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