Quantum chemical modelling of electron polarons and excitons in ABO3perovskites
- 16 August 2000
- journal article
- Published by IOP Publishing in Journal of Physics: Condensed Matter
- Vol. 12 (35) , L557-L562
- https://doi.org/10.1088/0953-8984/12/35/101
Abstract
Quantum chemical calculations using the intermediate neglect of the differential overlap (INDO) method, combined with the large unit cell periodic model argue for an existence of the self-trapped electrons in KNbO3 and KTaO3 perovskite crystals. An electron in the ground state occupies predominantly t2g orbital of a Nb4+ ion. Its orbital degeneracy is lifted by a combination of the breathing and Jahn-Teller modes where four nearest equatorial O atoms are displaced outwards and two oxygens shift inwards along the z axis. Triplet exciton is shown to be in a good approximation of a pair of nearest Jahn-Teller electron and hole polarons (a bipolaron) which is very likely responsible for the 'green' luminescence observed in these crystals.Keywords
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