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).

DOI: 10.1088/0953-8984/22/22/225405

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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