Lookup NU author(s): Dr Mark Rayson,
Professor Patrick Briddon
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
In this work, the ability of methods based on empirical potentials to simulate the effects of radiation damage in graphite is examined by comparing results for point defects, found using ab initio calculations based on density functional theory (DFT), with those given by two state of the art potentials: the Environment-Dependent Interatomic Potential (EDIP) and the Adaptive Intermolecular Reactive Empirical Bond Order potential (AIREBO). Formation energies for the interstitial, the vacancy and the Stone-Wales (5775) defect are all reasonably close to DFT values. Both EDIP and AIREBO can thus be suitable for the prompt defects in a cascade, for example. Both potentials suffer from arefacts. One is the pinch defect, where two alpha-atoms adopt a fourfold-coordinated sp(3) configuration, that forms a cross-link between neighbouring graphene sheets. Another, for AIREBO only, is that its ground state vacancy structure is close to the transition state found by DFT for migration. The EDIP fails to reproduce the ground state self-interstitial structure given by DFT, but has nearly the same formation energy. Also, for both potentials, the energy barriers that control diffusion and the evolution of a damage cascade, are not well reproduced. In particular the EDIP gives a barrier to removal of the Stone-Wales defect as 0.9 eV against DFT's 4.5 eV. The suite of defect structures used is provided as supplementary information as a benchmark set for future potentials.
Author(s): Latham CD, McKenna AJ, Trevethan TP, Heggie MI, Rayson MJ, Briddon PR
Publication type: Article
Publication status: Published
Journal: Journal of Physics: Condensed Matter
Print publication date: 12/08/2015
Online publication date: 23/07/2015
Acceptance date: 17/02/2015
ISSN (print): 0953-8984
ISSN (electronic): 1361-648X
Publisher: Institute of Physics Publishing Ltd.
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