Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 63: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles IV (jointly with TT)

O 63.1: Topical Talk

Thursday, March 29, 2012, 10:30–11:00, HE 101

Random phase approximation and GW for correlated systems — •Patrick Rinke — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany

In the quest for finding an “optimal" first principles electronic structure method, that combines accuracy and tractability with transferability across different chemical environments and dimensionalities (e.g. molecules, wires/tubes, surfaces, solids), the treatment of exchange and correlation in terms of “exact-exchange plus correlation in the random-phase approximation (EX+cRPA)” offers a promising avenue. Likewise one can express the same level of theory in the Green’s function context through the GW approximation, which has the additional advantage that quasiparticle spectra as measured by direct and inverse photoemission become accessible. For lanthanide and actinide oxides as prototypical f-electron solids, I will demonstrate that GW calculations yield spectral properties in good agreement with experiment, provided a suitable starting point like density-functional theory in the local-density approximation augmented by Hubbard U corrections (LDA+U) is used [1]. For the f-electron metal Cerium, for which (semi)local DFT functionals fail to reproduce the isostructural α-γ phase transition, EX+cRPA calculations based on hybrid functionals yield a double minimum in the total energy versus volume curve, indicative of the phase transition. For correlations in molecular systems, I will contrast EX+cRPA with GW and discuss recent schemes that go beyond cRPA [2]. [1] H. Jiang, et al., Phys. Rev. Lett. 102, 126403 (2009), [2] J. Paier et al., arXiv:cond-mat/1111.0173