Modification of excitation and charge transfer in cavity quantum-electrodynamical chemistry

Proceedings Of The National Academy Of Sciences Of The United States Of America 116 (11), 4883 - 4892 (2019)

Modification of excitation and charge transfer in cavity quantum-electrodynamical chemistry

Christian Schäfer, Michael Ruggenthaler, Heiko Appel, Angel Rubio

Energy transfer in terms of excitation or charge is one of the most basic processes in nature, and understanding and controlling them is one of the major challenges of modern quantum chemistry. In this work, we highlight that these processes as well as other chemical properties can be drastically altered by modifying the vacuum fluctuations of the electromagnetic field in a cavity. By using a real-space formulation from first principles that keeps all of the electronic degrees of freedom in the model explicit and simulates changes in the environment by an effective photon mode, we can easily connect to well-known quantum-chemical results such asDexter charge-transfer and Fo¨ rster excitation-transfer reactions,taking into account the often-disregarded Coulomb and selfpolarization interaction. We find that the photonic degrees of freedom introduce extra electron–electron correlations over large distances and that the coupling to the cavity can drastically alter the characteristic charge-transfer behavior and even selectively improve the efficiency. For excitation transfer, we find that the cavity renders the transfer more efficient, essentially distanceindependent, and further different configurations of highest efficiency depending on the coherence times. For strong decoherence (short coherence times), the cavity frequency should be in between the isolated excitations of the donor and acceptor, while for weak decoherence (long coherence times), the cavity should enhance a mode that is close to resonance with either donor or acceptor. Our results highlight that changing the photonic environment can redefine chemical processes, rendering polaritonic chemistry a promising approach toward the control of chemical reactions.

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We thank Arunangshu Debnath and Johannes Flick for insightful discussions. This work was supported by European Research Council Grant ERC-2015-AdG-694097 and partially supported by Federal Ministry of Education and Research Grant RouTe-13N14839.

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