HR: 10:50h
AN: MR12A-03 INVITED    [Abstracts]
TI: Ab-initio study of transition-metal compounds through a consistent, linear-response LDA+U approach
AU: * Cococcioni, M
EM: matteo@umn.edu
AF: Department of Chemical Engineering and Materials Science, 421 Washington Av SE, Minneapolis, MN 55455, United States
AB: Hubbard U-corrected LDA or GGA have proven very effective in describing several systems characterized by strongly localized electronic states for which these standard approximations to DFT fail. I introduce here our scheme to evaluate the effective electronic interaction of the "+U" functional in a fully consistent way. This approach is based on the linear response of the considered system to a potential shift acting on the localized orbitals of the correlated sites. Using the occupations of these orbitals as the relevant electronic degrees of freedom we compute the needed on-site electronic coupling as the difference between the inverse of the bare and fully interacting response matrices. The computed U thus corresponds to the effective kernel of the electron-electron on-site interaction entering the second quantization expression of the "+U" energy functional. In this way the strength of the "+U" correction is consistently evaluated from the same DFT scheme we aim to correct and the LDA+U is transformed in a completely ab-initio method with no need for any semi-empirical or apriori evaluation of the effective coupling. The results are also largely independent on the choice of the localized orbitals: the same occupation matrix that enters the expression of the "+U" correction is consistently used to compute the effective interaction parameter. A further development in this approach also allowed us to obtain the the effective U "auto-consistently" from a correlated (LDA+U) ground state. With this approach we successfully studied the structural, electronic, chemical and electrochemical properties of several transition-metal compounds. Examples of applications will include minerals in the Earth's interior [1], cathode materials for next-generation lithium batteries [2] and catalytic reactions on molecules [3,4]. [1] M. Cococcioni and S. de Gironcoli, PRB (2005). [2] F. Zhou, M. Cococcioni, A. C. Marianetti, D. Morgan and G. Ceder, PRB (2004). [3] H. J. Kulik, M. Cococcioni, D. Scherlis and N. Marzari, PRL (2006). [4] D. A. Scherlis, M. Cococcioni, P. Sit, and N. Marzari, JPC (2007).
DE: 3900 MINERAL PHYSICS
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting