A NEW MODEL FOR THE SELF-TRAPPED EXCITON IN ALKALI-HALIDES.
J PHYS-CONDENS MAT
3125 - 3138.
We report a quantum mechanical study of the structural and spectroscopic properties of the self-trapped exciton in LiCl. Our method interfaces the quantum cluster calculations on a Li-10Cl4 cluster with a Mott-Littleton treatment of the relaxation of the surrounding lattice. Calculations on the V(k) centre give structures that are in very good agreement with Mott-Littleton calculations, and yield optical absorption energies that compare well with experimental values. Our study of the triplet ground state of the self-trapped exciton reveals a minimum energy structure of C2v symmetry caused by a small off-centre displacement (of congruent-to 0.07 angstrom) of the Cl2- (V(k)) ions which comprise the hole component of the exciton. The electron is in a largely delocalized state around the hole with both components localized more on the Cl ion that is displaced towards the perfect lattice site. The magnitude of the off-centre displacement is much less than in the earlier studies of Song et al. A key feature in the success of these calculations was the self-consistent polarization of the surrounding lattice to the quantum cluster.
|Title:||A NEW MODEL FOR THE SELF-TRAPPED EXCITON IN ALKALI-HALIDES|
|Keywords:||NON-RADIATIVE DECAY, H CENTER PRODUCTION, INITIAL PRODUCTION, LATTICE-DEFECTS, CRYSTALS, CONFIGURATION, LUMINESCENCE, RELAXATION, CHLORIDES, CREATION|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy|
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