Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 25: POSTER Electronic Structure and Spectroscopy

CPP 25.1: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Theoretical investigation of the excited states of tungstate molecular groups in zinc tungstate crystals — •Tatiana Nikolaenko, Sergiy Nedilko, and Yuriy Hizhnyi — Faculty of Physics, Kyiv National Taras Shevchenko University, 2, block 1, Hlushkova av., 03680, Kyiv, Ukraine

The crystals of zinc ZnWO₄ tungstate are well known scintillation and laser materials, which are used in different applications. The composition and structure of the luminescence centers in zinc tungstate are still the subjects of discussion. Nevertheless, it is commonly believed that the optical and luminescence properties of ZnWO₄ are determined largely by their anionic structural components, the tungstate groups. In order to study the luminescence processes in zinc tungstate theoretically, we perform quantum-chemical calculations of the electronic structure of WO₆⁶⁻ molecular groups in ZnWO₄.

Molecular cluster of ZnWO₄ consisted of WO₆⁶⁻ group and the nearest Zn²⁺ cation was taken into consideration. Multiconfigurational self-consistent field wavefunctions of the cluster are calculated using GAMESS quantum chemistry package [1]. Dependencies of energies of the ground and excited electronic states of the cluster on several normal coordinates are obtained. The schemes of luminescence processes in ZnWO₄ are constructed using the obtained results. The origin of several bands in absorption and reflection spectra of the crystals is discussed on the base of the calculations.

[1] Schmidt M.W., et al., J. Comput. Chem., 14, 1347, (1993)