First-principles study of spin-state crossovers and hyperfine interactions of ferric iron in magnesium silicate perovskite1

Submitted for the MAR11 Meeting of The American Physical Society Sorting Category: 19.1 (C) First-principles study of spin-state crossovers and hyperfine interactions of ferric iron in magnesium silicate perovskite1 HAN HSU, University of Minnesota, PETER BLAHA, TU Vienna, MATTEO COCOCCIONI, RENATA WENTZCOVITCH, University of Minnesota — The spin-state crossover in iron-bearing MgSiO3 perovskite, the most abundant mineral in the Earth, may significantly affect the properties of Earth’s lower mantle. However, details of this phenomenon have been very unclear, owing to the complicated nature of this mineral, mainly the coexistence of ferrous and ferric iron. Using the density functional theory plus Hubbard U (DFT+U) methods, we investigated the spin states and hyperfine interactions of ferric iron in this mineral. We show that a crossover from high-spin to low-spin state occurs within the lower-mantle pressure range, and it is accompanied by a noticeable volume reduction and an increase in iron nuclear quadrupole splitting (QS). These results are consistent with recent x-ray diffraction and Mössbauer spectroscopy measurements [K. Catalli et al., Earth Planet. Sci. Lett. 289, 68 (2010)]. 1This work is primarily supported by the MRSEC Program of NSF under DMR-0212302 and DMR-0819885, and partially supported by EAR0810212 and EAR-1047629. P.B. was supported by the Austrian Science Fund (P20271-N17). Calculations were performed at MSI. X Prefer Oral Session Prefer Poster Session Han Hsu [email protected] University of Minnesota Date submitted: 03 Dec 2010 Electronic form version 1.4