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First-principles study of the dynamic Jahn-Teller distortion of the neutral vacancy in diamond

Accepted version
Peer-reviewed

Repository DOI


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Authors

Prentice, JCA 
Monserrat, B 
Needs, RJ 

Abstract

First-principles density functional theory methods are used to investigate the structure, energetics, and vibrational motions of the neutral vacancy defect in diamond. The measured optical absorption spectrum demonstrates that the tetrahedral Td point group symmetry of pristine diamond is maintained when a vacancy defect is present. This is shown to arise from the presence of a dynamic Jahn-Teller distortion that is stabilized by large vibrational anharmonicity. Our calculations further demonstrate that the dynamic Jahn-Teller-distorted structure of Td symmetry is lower in energy than the static Jahn-Teller distorted tetragonal D2d vacancy defect, in agreement with experimental observations. The tetrahedral vacancy structure becomes more stable with respect to the tetragonal structure by increasing temperature. The large anharmonicity arises mainly from quartic vibrations, and is associated with a saddle point of the Born-Oppenheimer surface and a minimum in the free energy. This study demonstrates that the behavior of Jahn-Teller distortions of point defects can be calculated accurately using anharmonic vibrational methods. Our work will open the way for first-principles treatments of dynamic Jahn-Teller systems in condensed matter.

Description

Keywords

cond-mat.mes-hall, cond-mat.mes-hall, cond-mat.mtrl-sci, physics.comp-ph

Journal Title

Physical Review B - Condensed Matter and Materials Physics

Conference Name

Journal ISSN

2469-9950
2469-9969

Volume Title

95

Publisher

American Physical Society
Sponsorship
Engineering and Physical Sciences Research Council (EP/K014560/1)
EPSRC (1492220)
Engineering and Physical Sciences Research Council (EP/J017639/1)
Engineering and Physical Sciences Research Council (EP/P022596/1)
Engineering and Physical Sciences Research Council (EP/F032773/1)
We thank the Engineering and Physical Sciences Research Council (EPSRC) of the UK for financial support (EP/J017639/1). B.M. acknowledges Robinson College, Cambridge, and the Cambridge Philosophical Society for a Henslow Research Fellowship.