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The Jahn-Teller instability with accidental degeneracy

Stoneham, AM; Lannoo, M; (1969) The Jahn-Teller instability with accidental degeneracy. Journal of Physics and Chemistry of Solids , 30 (7) 1769 -1777. 10.1016/0022-3697(69)90245-5. Green open access

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The Jahn-Teller theorem predicts that orbitally degenerate complexes in solids can lower their energy by a distortion which lowers their symmetry. Exact degeneracy is not necessary for this instability; usually it suffices if the actual separation of the energy levels involved is less than the energy reduction which would result if they were exactly degenerate. We discuss various cases of accidental degeneracy in cubic and tetrahedral systems. With accidental degeneracy it is possible to get mixed distortions which involve both trigonal and tetragonal distortions. These have probably been observed for the negative vacancy in silicon, and possibly for the neutral vacancy in diamond. The theory is applied to both these cases, and it is compared with the earlier qualitative arguments of Watkins.

Type: Article
Title: The Jahn-Teller instability with accidental degeneracy
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/0022-3697(69)90245-5
Publisher version: http://dx.doi.org/10.1016/0022-3697(69)90245-5
Language: English
Additional information: Text made available to UCL Discovery by kind permission of Elsevier B.V., 2012
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/59781
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