Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 6: Focus Session: Frontiers of Electronic-Structure Theory: Correlated Electron Materials I (joint session O/MM/DS/TT/CPP)
MM 6.2: Talk
Monday, March 12, 2018, 10:45–11:00, HL 001
Steps in the exact Kohn-Sham potential of ensemble density-functional theory for excited states and their relation to the derivative discontinuity — •Matthew J. P. Hodgson1, Eli Kraisler1, Michael T. Entwistle2, Axel Schild3, and Eberhard K. U. Gross1,4 — 1MPI für Mikrostrukturphysik, D-06120 Halle, Germany — 2Dep. of Physics, Uni. of York, Heslington, YO10 5DD, UK — 3Lab. für Physikalische Chemie, ETH Zürich, 8093, Switzerland — 4Fritz Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem, 91904, Israel
An accurate approximation to the exchange-correlation (xc) part of the Kohn-Sham (KS) potential is essential for any density-functional calculation. Understanding the behaviour of the exact xc potential and developing improved approximations to it are crucial. The focus of calculations within density functional theory is usually on the ground state. However, knowledge of how the system responds to an excitation is important. In this talk we present the exact KS potential of an ensemble of the ground state and the first excited state of a 1D diatomic molecule. For this system, upon excitation, a small amount of charge transfers from one atom to the other. In the corresponding exact ensemble xc potential we find two plateaus: one that forms around the nucleus of the acceptor atom, associated with the derivative discontinuity of that atom, and another that forms around the donor atom and corresponds to a new phenomenon which we term the `charge-transfer derivative discontinuity'.