Title: Ab-initio non-relativistic quantum electrodynamics for quantum materials
Abstract: In recent years, research at the interface of chemistry, material science, and quantum optics has surged and now opens new possibilities to study strong light-matter interactions at different limits [1,2]. Combining theoretical concepts from the fields of material science and quantum optics presents an opportunity to create a predictive theoretical and computational approach to describe cavity correlated electron-nuclear dynamics from first principles. Towards this overarching goal, we introduce a general time-dependent density-functional theory to study correlated electron, nuclear and photon interactions on the same quantized footing .
In this talk, I discuss how density-functional theory can be generalized to a quantum-electrodynamical density-functional theory (QEDFT) and show how exchange-correlation potentials can be devised. Further, I discuss the linear-response theory for QEDFT  and emerging ab-initio lifetimes that are now within computational reach. Considering electrons, nuclei and photons on the same quantized footing, we find cavity-modulated molecular motion of molecules in optical cavities , as well as new light-matter correlated observables for a new type of spectroscopy. Further, we use this novel framework to study how the potential-energy surfaces of a CO bond stretching in a Formaldehyde molecule is modified under strong-light matter coupling, demonstrating the novel abilities to alter and open new chemical reaction pathways as well as to create new hybrid states of light and matter in this regime.
Our work opens an important new avenue in introducing ab-initio methods to the nascent field of collective strong light-matter interactions.
 J. Flick, N. Rivera, P. Narang, Nanophotonics 7 (9) 1479-1501 (2018).
 T. Ebbesen, Acc. Chem. Res. 49, 11, 2403-2412 (2016).
 J. Flick, P. Narang, Phys. Rev. Lett. 121, 113002 (2018).
 J. Flick, et al., arxiv 1803.02519 (2018).