Pressure induced high spin to low spin transition in magnesiowüstite

Using a rotationally invariant formulation of LDA + U, we report a successful study of the high spin (HS)/ low spin (LS) transition in low solute concentration magnesiowüstite (Mw), (Mg_1-xFe_x)O, (x < 20%), the second most abundant phase in Earth's lower mantle. The HS state crosses over smoothly to the LS state passing through an insulating mixed spins state where properties change continuously, as seen experimentally. These encouraging results indicate this method should enable first principles studies of strongly correlated iron-bearing minerals, a major class of mineral physics problems.