Keywords:First-principles method, internally consistent LSDA+U, MgSiO3, postperovskite
MgSiO3 bridgmanite (Br) will undergoes a post-perovskite (PPv) phase transition[1,2,3] in the pressure (P) and temperature (T) conditions corresponding to the Earth’s D” layer. Therefore, The phase change is recognized as the key for understanding the seismological observations in the D” layer. However, to date, it is still a challenging subject to determine the phase transition boundary preciously in the geophysically relevant Fe and Al-bearing compositions. Based on the first-principles methods combined with the internally consistent LSDA+U method and the lattice dynamics approach, the high-P,T thermodynamics of the MgSiO3 phases are directly calculated with incorporation of 6.25 mol% of Fe2+, Fe3+Fe3+, Fe3+Al3+, and Al3+Al3+ [4,5]. Using calculated free energies, we determine the PPv phase boundaries for Fe and Al-bearing compositions. Our results show that at 2500 K, incorporations of Fe3+Fe3+ and Fe3+Al3+ span coexisting domains between Br and PPv significantly with lowering the transition pressure, in contrast to the Fe2+ and Al3+Al3+-bearing cases.
 M. Murakami, K. Hirose, K. Kawamura, N. Sata, and Y. Ohishi, Science 304, 855 (2004).
 A. Oganov, and S. Ono, Nature 430, 445 (2004).
 T. Tsuchiya, J. Tsuchiya, K. Umemoto, and R. M. Wentzcovitch, Earth. Planet. Sci. Lett. 224, 241 (2004).
 J. Tsuchiya, and T. Tsuchiya, Proc. Natl. Acad. Sci. USA 105, 19160 (2008).
 A. Metsue, and T. Tsuchiya, Geophys. J. Int. 190, 310 (2012).