Theoretical explanation of the octahedral distortion in FeF2 and MgF2
- Author(s)
- Alexander Riss, Peter Blaha, Karlheinz Schwarz, Josef Zemann
- Abstract
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(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Technische Universität Wien
- Journal
- Zeitschrift für Kristallographie : international journal for structural, physical, and chemical aspects of crystalline materials
- Volume
- 218
- Pages
- 585-589
- No. of pages
- 5
- ISSN
- 0044-2968
- DOI
- https://doi.org/10.1524/zkri.218.9.585.20680
- Publication date
- 2003
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 1051 Geology, Mineralogy
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/theoretical-explanation-of-the-octahedral-distortion-in-fef2-and-mgf2(70e30ffd-f7ca-4370-b963-2aa89c29eb5e).html