Calculation of the spectral, structural, and electronic properties of NaCrSi₂O₆ and LiCrSi₂O₆ crystals

Spectral, structural and electronic properties of two Cr ³⁺-bearing systems (NaCrSi₂O₆, LiCrSi ₂O₆) have been theoretically modeled using two different approaches: semi-empirical model of crystal field, in the framework of the Exchange Charge Model and two ab initio DFT-based calculations, as implemented in the CASTEP module [1] of Materials Studio package [2] and, for reliability, CRYSTAL09 code [3]. The first one allows for calculations of the electronic levels of sixfold coordinated Cr³⁺ ions in a crystal field of host's ligands and direct comparison with experimental absorption spectra [4]. The latter two allow for the analysis of the band structure and density of states (DOS), after optimization of the crystal lattice structures of these materials. In particular, a special attention was paid to the energetic position of the Cr³⁺ 3d states. All obtained results are compared with corresponding experimental values and discussed.