HYBRIDIS: Dispersion forces in media — A hybrid approach combining macroscopic quantum electrodynamics with microscopic density functional theory

• Applicants: Professor Dr. Stefan Yoshi Buhmann; Privatdozent Dr. Michael Walter
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403680418

Dispersion forces are ubiquitous effective electromagnetic interactions between polarisable molecular systems. They have traditionally been studied by two very different scientific communities from seemingly incompatible points of view: Physical chemistry has painted a microscopic picture where these forces are a long-range interaction between the charged particles constituting the molecular systems. From the macroscopic, quantum optics perspective, the London dispersion force is the short-range, non-retarded limit of the full quantum electrodynamical interaction between molecular multipoles under the influence of continuous background media and bodies. With this interdisciplinary project, we intend to combine the complementary strengths of macroscopic quantum electrodynamics and density functional theory into a powerful and efficient multi-scale framework for studying dispersion interactions of molecular ensembles under the influence of A. Polarisable background media and B. Dielectric and metallic surfaces. To allow for a range of experimentally relevant systems, the impact of charged or excited molecular systems as well as surface charges will also be considered. The new hybrid theory will combine knowledge and techniques from physical chemistry and quantum optics into a coherent whole: model assumptions of the macroscopic quantum electrodynamics approach will be underpinned with results from density functional simulations and conversely, effective quantum electrodynamics dispersion potentials will feed into density-functional studies of molecular ensembles. The proposed framework will be able to describe configurations such as multilayer molecular ensembles on charged surfaces or molecular interactions inside or on the surface of nano-droplets under realistic conditions. It will allow for a systematic study of the combined impact of excitations, background media and surfaces on the dispersion-force induced collective dynamics of molecular ensembles and hence pave the way towards new chemical design principles. The results will have an immediate impact on fields as diverse as physical chemistry, colloid physics and cell biology.

• DFG Programme: Research Grants