Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 47: Focused Session: Frontiers of Electronic Structure Theory 5 (jointly with HL and O)
TT 47.12: Talk
Wednesday, March 13, 2013, 19:00–19:15, H36
Interplay between H bond symmetrization and spin transition in є-FeOOH: insights from first principles — •Carmen Quiroga and Rossitza Pentcheva — Dept. of Earth and Environmental Sciences, University of Munich
Structural and electronic spin transitions in high-pressure є-FeOOH are studied using density functional theory calculations including an on-site Coulomb repulsion term. A high-spin to low-spin transition in trivalent iron is predicted at ∼58 GPa, in agreement with previous theoretical study [1] and experimental indications [2]. The spin transition is heralded by a second order P21nm to Pnnm phase transition at ∼43 GPa, driven by hydrogen bond symmetrization at the critical hydrogen bond O⋯O limit of ≃2.4 Å. Our results give indications of a possible connection between the symmetry of hydrogen bonds in є-FeOOH and the spin state of Fe3+, with important implications in disclosing the influence of water content in the mantle redox state.
Funding by DFG SPP1236 (PE883/8-1) is acknowledged.
[1] Otte et al. Phys. Rev. B 80, 205116 (2009).
[2] Gleason et al. In preparation.