Analysis of the local structure around Cr3+ centers in perovskite KMgF3 using both ab initio (DFT) and semi-empirical (SPM) calculations

- The local structure around Cr3+ centers in perovskite KMgF3 crystal investigated.
- Both an ab-initio, density functional theory, and a semi empirical, superposition model applied.
- Structural mechanisms for Cr3+ centers through various modeling steps investigated.
- Significant structural changes around Cr3+ centers induced by Mg2+ or K+ vacancies determined.

The local structure around Cr3+ centers in perovskite KMgF3 crystal have been investigated through the applications of both an ab-initio, density functional theory (DFT), and a semi empirical, superposition model (SPM), analyses. A supercell approach is used for DFT calculations. All the tetragonal (Cr3+-VMg and Cr3+-Li+), trigonal (Cr3+-VK), and CrF5O cluster centers have been considered with various structural models based on the previously suggested experimental inferences. The significant structural changes around the Cr3+ centers induced by Mg2+ or K+ vacancies and the Li substitution at those vacancy sites have been determined and discussed by means of charge distribution. This study provides insight on both the roles of Mg2+ and K+ vacancies and Li+ ion in the local structural properties around Cr3+ centers in KMgF3.