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Title: Ab-initio modelling of defects in MgO
Authors: Gilbert, C.A.
Smith, Roger
Kenny, Steven D.
Keywords: Magnesium oxide
Issue Date: 2007
Publisher: © Elsevier
Citation: GILBERT, C.A., SMITH, R. and KENNY, S.D., 2007. Ab-initio modelling of defects in MgO. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 255 (1), pp. 166 - 171.
Abstract: The energetics of the key defects that are observed to occur during simulations of radiation damage in MgO are analysed using density functional theory. The results are compared with those from the empirical potentials used to carry out the radiation damage studies. The formation energies of vacancies, interstitials, Frenkel pairs, di-vacancies and di-interstitials are calculated as a function of the increasing supercell size in order to ensure good convergence. The supercell geometries were chosen to maximise the separation distance between periodic images. Their sizes ranged from cells containing 32 atoms up to cells containing 180 atoms. Results are presented for the formation energies of the first, second and third nearest neighbour defects. Results show that the di-vacancy formation energy is in the region of 4–6 eV and that formation energies for di-interstitials are more than double this, lying in the range 12–16 eV. Comparison of the results show that empirical potentials overestimate the formation energy of di-vacancies by 1–3 eV and underestimate the formation energies of di-interstitials by about 1–2 eV. The relative stability of the defects is, however, correctly predicted by the empirical potentials. The direction and the magnitude of the displacements of the atoms surrounding the defects are in good agreement for all the systems containing interstitials. For the systems containing vacancies the direction of the displacements are in agreement but the empirical potentials predict larger displacements in all cases.
Description: This article was published in the journal, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms [© Elsevier] in a special issue, Computer Simulation of Radiation Effects in Solids — Proceedings of the Eighth International Conference on Computer Simulation of Radiation Effects in Solids (COSIRES 2006). The definitive version is available at: http://dx.doi.org/10.1016/j.nimb.2006.11.044
Version: Accepted for publication
DOI: 10.1016/j.nimb.2006.11.044
URI: https://dspace.lboro.ac.uk/2134/11639
Publisher Link: http://dx.doi.org/10.1016/j.nimb.2006.11.044
ISSN: 0168-583X
Appears in Collections:Published Articles (Maths)

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