Quantum chemical simulations of hole self-trapping in corundum
P W M Jacobs; E A Kotomin; A Stashans; E V Stefanovich; I Tale; P W M Jacobs; Center for Chem. Phys., Univ. of Western Ontario, London, Ont., Canada; E A Kotomin; Center for Chem. Phys., Univ. of Western Ontario, London, Ont., Canada; A Stashans; Center for Chem. Phys., Univ. of Western Ontario, London, Ont., Canada; E V Stefanovich; Center for Chem. Phys., Univ. of Western Ontario, London, Ont., Canada; I Tale; Center for Chem. Phys., Univ. of Western Ontario, London, Ont., Canada
Журнал:
Journal of Physics: Condensed Matter
Дата:
1992-09-14
Аннотация:
Microscopic quantum chemical calculations and simulations based on atom-atom potentials have been undertaken for hole self-trapping in pure corundum ( alpha -Al<sub>2</sub>O<sub>3</sub>) crystals. A comparison of different modes of ionic relaxation during hole trapping has shown that the inward Jahn-Teller 40% displacement of two O ions accompanied by the 20% outward displacement of the two nearest Al ions is energetically the most favourable. Eighty per cent of the hole density is concentrated on these two O ions, thus confirming that a small-radius two-site polaron model similar to that for alkali halides (the V<sub>K</sub> centre), is applicable here. The calculated absorption energy of the STH (2.9 eV) is close to that observed experimentally.
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