Analysis of paramagnetic 3d ions (Cr3+ and Fe3+) centers in fluoroelpasolite Cs2NaGaF6 crystal by both DFT and SPM calculations

The structural properties of 3d ions (Cr3+ and Fe3+) centers in Cs2NaGaF6 have been investigated by performing density functional theory (DFT) and semi-empirical superposition model (SPM) calculations. The local geometry (i.e. equilibrium ligand distance and angles between the host cation ion (Cs+, Na+, or Ga3+) and F ligands) for pure, Cr3+ doped and Fe3+ doped structures have been determined after a fully relaxed geometry optimization at each lattice site. The previous experimental zero-field splitting (ZFS) parameters (ZFSPs) have been analyzed by SPM calculations using the obtained structural properties from DFT. The combination of two methods provide us to confirm the main result of the previous electron magnetic resonance and optical investigations stating that transition metal (TM) ions substitute for octahedral sites instead of being distributed randomly in the lattice of Cs2NaGaF6.