Abstract
Molecular dynamics simulation is used to study radiation damage cascades in graphite. High statistical precision is obtained by sampling a wide energy range (100–2500eV) and a large number of initial directions of the primary knock-on atom. Chemical bonding is described using the Environment Dependent Interaction Potential for carbon. Graphite is found to exhibit a radiation response distinct from metals and oxides primarily due to the absence of a thermal spike which results in point defects and disconnected regions of damage. Other unique attributes include exceedingly short cascade lifetimes and fractal-like atomic trajectories. Unusually for a solid, the binary collision approximation is useful across a wide energy range, and as a consequence residual damage is consistent with the Kinchin–Pease model. The simulations are in agreement with known experimental data and help to clarify substantial uncertainty in the literature regarding the extent of the cascade and the associated damage.
Highlights
Despite being one of the original nuclear materials, remarkably few molecular dynamics simulations have been performed to understand radiation response in graphite
We report graphite cascade simulations using the Environment Dependent Interaction Potential (EDIP) for carbon [26,27] coupled with the standard Ziegler–Biersack–Littmack (ZBL) potential [28] to describe close-range pair interactions
The radiation damage cascades are simulated using molecular dynamics (MD) with equilibrium interactions governed by the EDIP methodology for carbon [26,27]
Summary
Despite being one of the original nuclear materials, remarkably few molecular dynamics simulations have been performed to understand radiation response in graphite. Whereas a vast computational literature exists for radiation processes in metals and oxides A great number of radiation cascade simulations were performed over the following decades, facilitated by the development of the embedded atom method [15,16] for metals and Buckingham-type potentials [17,18] for ionic solids and oxides.
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