Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 91: Focus Session: Frontiers of Electronic Structure Theory - Non-Equilibrium Phenomena at the Nano-Scale VI (organized by O)
TT 91.10: Vortrag
Donnerstag, 3. April 2014, 13:00–13:15, TRE Ma
Self-consistent dynamical embedding in real space — •Wael Chibani1, Xinguo Ren1,2, Patrick Rinke1, and Matthias Scheffler1 — 1Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 2Key Laboratory of Quantum Information, USTC, Hefei, China
Density-functional theory with its local-density (LDA) and generalized gradient approximations (GGA) is known to fail for localized states. To extend ab initio approaches to this domain, we have devised an embedding scheme that facilitates the treatment of the physically important part of a system with electronic structure methods, that are computationally too expensive for periodic systems, whereas the rest of the periodic system is treated with computationally less demanding approaches, i.e. LDA/GGA, in a self-consistent manner. Our scheme is based on the concept of dynamical mean-field theory (DMFT) [1]. However, in contrast to the original DMFT formulation for correlated model Hamiltonians, we consider here the unit cell as embedded cluster in an ab initio way, that includes all electronic degrees of freedom. The performance of our scheme is demonstrated by treating the embedded region with hybrid functionals for simple bulk systems, e.g. Si or NiO. The total energy and the density of states converge rapidly with respect to the computational parameters and approach their bulk limit with increasing cluster size. By treating the embedded region with GW we were able to improve the band gap using only a small cluster. The effect of self-consistency in GW for the embedded region will also be addressed. [1] A. Georges et al., Rev. Mod. Phys. 68,14 (2006)