Structural, electronic, and magnetic properties of Fe2SiO4 fayalite: Comparison of LDA and GGA results

Matteo Cococcioni, Andrea Dal Corso, and Stefano de Gironcoli
Phys. Rev. B 67, 094106 – Published 7 March 2003
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Abstract

We present a first principle investigation of the structural, electronic and magnetic properties of Fe2SiO4 Fayalite, the iron-rich end member of the (Mg,Fe)2SiO4 olivine solid solution, naturally occurring in the Earth’s upper mantle. Local spin-density approximation and spin-polarized generalized gradient approximation (σGGA) results are compared; σ-GGA appears to provide an overall better description of the structural properties. The ground-state spin configuration is investigated and the antiferromagnetic spin arrangement consistent with a superexchange mechanism through oxygen orbitals is found to be preferred. Electronic structure calculations using both exchange and correlation functionals predict a metallic ground state, contrary to experimental evidence that indicates a insulating, possibly Mott-Hubbard, behavior. In fact, by comparison of our DFT results with the RPA solution of a simple ad hoc Hubbard model, we were able to estimate the average short-range electron-electron repulsion parameter U. This quantity turns out to be larger than the relevant band width, and therefore, we support the Mott-Hubbard nature of the experimentally observed insulating behavior.

  • Received 9 August 2002

DOI:https://doi.org/10.1103/PhysRevB.67.094106

©2003 American Physical Society

Authors & Affiliations

Matteo Cococcioni, Andrea Dal Corso, and Stefano de Gironcoli

  • SISSA–Scuola Internazionale Superiore di Studi Avanzati and INFM-DEMOCRITOS National Simulation Center, via Beirut 2-4, I-34014 Trieste, Italy

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Vol. 67, Iss. 9 — 1 March 2003

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