Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 33: Focus Session: Frontiers of Electronic-Structure Theory: Correlated Electron Materials IV (joint session O/MM/DS/TT/CPP)
MM 33.2: Talk
Wednesday, March 14, 2018, 11:00–11:15, HL 001
Density functional theory of electron transfer beyond the Born-Oppenheimer approximation: case study of LiF — •Chen Li1, Ryan Requist1, and Eberhard. K. U. Gross1,2 — 1Max Planck Institute of Microstructure Physics, Halle, Germany — 2Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
We demonstrate that beyond Born-Oppenheimer (BO) effects can be accurately and seamlessly incorporated within a density functional framework. In alkali halides like LiF, there is an abrupt change in the ground state electronic distribution due to an electron transfer at a critical bond length R=Rc. We find that nonadiabatic electron-nuclear coupling produces a sizable elongation of the critical Rc by 0.5 Bohr, an effect which is very accurately captured by a simple and rigorously-derived nuclear mass-dependent correction to the exchange-correlation potential in density functional theory. Since this nonadiabatic term depends on gradients of the nuclear wave function and conditional electronic density, ∇R χ(R) and ∇R n(r,R), it couples the Kohn-Sham equations at neighboring R points. Motivated by an observed localization of nonadiabatic effects in nuclear configuration space, we propose an approximation that reduces the search for nonadiabatic density functionals to the search for a single function. This work is a step towards bringing density functional theory beyond the limitations of the BO approximation.