Theoretical explanation of the octahedral distortion in FeF2 and MgF2
- Autor(en)
- Alexander Riss, Peter Blaha, Karlheinz Schwarz, Josef Zemann
- Abstrakt
The equilibrium geometries of rutile type FeF2 and MgF 2 are determined using precise density functional theory calculations that lead to good agreement with experimental data. The strong deviation from the "ideal" octahedral geometry in FeF2 comes from the Fe2+ ion with the d6 configuration in the high-spin state, which would require a singly occupied spin-down d orbital. The stability can only be understood by going beyond the first coordination shell considering direct Fe-Fe interactions mainly along the c-axis. The orbital population of the various Fe-d orbitals is analyzed using constraint distortions between the ideal and the equilibrium structure. Above a critical Fe-Fe distance of about 3.15 A° the population numbers change drastically, a single Fe-d spin down orbital becomes occupied and the system can relax to an insulating state. In MgF2 no such d-orbitals are present and thus the distortions are much smaller.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Technische Universität Wien
- Journal
- Zeitschrift für Kristallographie : international journal for structural, physical, and chemical aspects of crystalline materials
- Band
- 218
- Seiten
- 585-589
- Anzahl der Seiten
- 5
- ISSN
- 0044-2968
- DOI
- https://doi.org/10.1524/zkri.218.9.585.20680
- Publikationsdatum
- 2003
- Peer-reviewed
- Ja
- ÖFOS 2012
- 1051 Geologie, Mineralogie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/70e30ffd-f7ca-4370-b963-2aa89c29eb5e