Symmetry-breaking and reconstruction at point defects in solids

ORAL

Abstract

Point defects are a universal feature of crystalline materials. Their identification is often addressed by combining experimental measurements with theoretical models. The standard approach of simulating defects is, however, prone to miss the ground state atomic configurations associated with energy-lowering reconstructions from the idealised crystallographic environment.1–5 Missed ground states compromise the accuracy of calculated properties.



To address this issue, we report an approach to efficiently navigate the defect configurational landscape using targeted bond distortions and rattling.6 Application of our workflow to a range of materials (CdTe, GaAs, Sb2S3, Sb2Se3, CeO2) reveals symmetry breaking in each host crystal that is not found via conventional local minimization techniques. The point defect distortions are classified by the associated physico-chemical factors. We demonstrate the impact of these defect distortions on derived properties, including formation energies, concentrations and charge transition levels. Our work presents a step forward for quantitative modelling of imperfect solids.

1. Arrigoni, M. & Madsen, G. K. H. npj Comput Mater (2021)

2. Mosquera-Lois, I. & Kavanagh, S. R. Matter (2021)

3. Lany, S. & Zunger, A. Phys. Rev. Lett. (2004)

5. Kavanagh, S. R., Scanlon, D. O., Walsh, A. & Freysoldt, C. Faraday Discuss. (2022)

6. Mosquera-Lois, I., Kavanagh, S. R., Walsh, A., Scanlon, D. O. npj Comput Mater (Under Review)

*I.M.L. and S.R.K thank La Caixa Foundation for funding (ID 100010434, fellowship code LCF/BQ/EU20/11810070) and the EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials (CDTACM)(EP/S023259/1) respectively for funding postgraduate studentships. DOS acknowledges support from the EPSRC (EP/N01572X/1) and from the European Research Council, ERC (Grant No. 758345). Via membership of the UK's HEC Materials Chemistry Consortium, which is funded by the EPSRC (EP/L000202, EP/R029431, EP/T022213), this work used the UK Materials and Molecular Modelling (MMM) Hub (Thomas EP/P020194 and Young EP/T022213).

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Publication: Kavanagh, S. R., Walsh, A. & Scanlon, D. O. ACS Energy Lett. (2021)
Mosquera-Lois, I. & Kavanagh, S. R. Matter (2021)
Kavanagh, S. R., Scanlon, D. O., Walsh, A. & Freysoldt, C. Faraday Discuss. (2022)
Mosquera-Lois, I., Kavanagh, S. R., Walsh, A., Scanlon, D. O. npj Comput Mater (Under Review)
Mosquera-Lois, I., Kavanagh, S. R., Walsh, A., Scanlon, D. O. J Open Source Software (Under Review)

Presenters

  • Seán R Kavanagh

    • University College London

Authors

  • Seán R Kavanagh

    • University College London

  • Irea Mosquera-Lois

    • Department of Materials, Imperial College London

  • Aron Walsh

    • Imperial College London

  • David O Scanlon

    • Department of Chemistry, University College London
    • University College London