Ab-initio Optimized Effective Potentials for Real Molecules in Optical Cavities: Photon Contributions to the Molecular Ground state

ACS Photonics 5, 992 - 1005 (2018)

Ab-initio Optimized Effective Potentials for Real Molecules in Optical Cavities: Photon Contributions to the Molecular Ground state

Johannes Flick,Christian Schäfer,Michael Ruggenthaler,Heiko Appel, Angel Rubio

We introduce a simple scheme to efficiently compute photon exchange-correlation contributions due to the coupling to transversal photons as formulated in the newly developed quantum- electrodynamical density-functional theory (QEDFT).(1−5) Our construction employs the optimized-effective potential (OEP) approach by means of the Sternheimer equation to avoid the explicit calculation of unoccupied states. We demonstrate the efficiency of the scheme by applying it to an exactly solvable GaAs quantum ring model system, a single azulene molecule, and chains of sodium dimers, all located in optical cavities and described in full real space. While the first example is a two-dimensional system and allows to benchmark the employed approximations, the latter two examples demonstrate that the correlated electron-photon interaction appreciably distorts the ground-state electronic structure of a real molecule. By using this scheme, we not only construct typical electronic observables, such as the electronic ground-state density, but also illustrate how photon observables, such as the photon number, and mixed electron-photon observables, for example, electron–photon correlation functions, become accessible in a density-functional theory (DFT) framework. This work constitutes the first three-dimensional ab initio calculation within the new QEDFT formalism and thus opens up a new computational route for the ab initio study of correlated electron–photon systems in quantum cavities.

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Doi
http://dx.doi.org/10.1021/acsphotonics.7b01279
arxiv
http://arxiv.org/abs/1710.07999
Notes
We would like to thank Claudiu Genes, Camilla Pellegrini,and Ilya V. Tokatly for insightful discussions and acknowledge financial support from the European Research Council (ERC-2015-AdG-694097), by the European Union's H2020 program under GA no.676580 (NOMAD), and the Austrian Science Fund (FWF P25739-N27).

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