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On the validity of empirical potentials for simulating radiation damage in graphite: a benchmark

Lookup NU author(s): Dr Mark Rayson, Professor Patrick Briddon

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

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.


Publication metadata

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

Year: 2015

Volume: 27

Issue: 31

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.

URL: http://dx.doi.org/10.1088/0953-8984/27/31/316301

DOI: 10.1088/0953-8984/27/31/316301


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