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- Title
The d Orbital Multi Pattern Occupancy in a Partially Filled d Shell: The KFeF 3 Perovskite as a Test Case.
- Authors
Pascale, Fabien; Mustapha, Sami; D'Arco, Philippe; Dovesi, Roberto
- Abstract
The occupancy of the d shell in KFeF 3 is t 2 g 4 e g 2 , with five α and one β electrons. The Jahn–Teller lift of degeneracy in the t 2 g sub-shell produces a tetragonal relaxation of the unit cell (4.09 vs. 4.22 Å, B3LYP result) not observed experimentally. In order to understand the origin of this apparent contradiction, we explored, with a 2 × 2 × 2 supercell (40 atoms per cell), all possible local structures in which contiguous Fe atoms have a different occupancy of the t 2 g orbitals with the minority spin electron. A total of 6561 configurations (with occupancies from (8,0,0) to (3,2,2) of the 3 t 2 g orbitals of the 8 Fe atoms) have been explored, with energies in many cases lower (by up to 1550 μ E h per 2 Fe atoms) than the one of the fully ordered case, both for the ferromagnetic and the anti-ferromagnetic solutions. The results confirm that the orientation of the β d electron of Fe influences the electrostatics (more efficient relative orientation of the Fe quadrupoles of the d shell) of the system, but not the magnetic interactions. Three hybrid functionals, B3LYP, PBE0, and HSE06, provide very similar results.
- Subjects
ELECTRON spin; UNIT cell; JAHN-Teller effect; ELECTROSTATICS; ELECTRONS
- Publication
Materials (1996-1944), 2023, Vol 16, Issue 4, p1532
- ISSN
1996-1944
- Publication type
Article
- DOI
10.3390/ma16041532