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Advances in nanoscience and material science point towards a new era when materials with unprecedented properties will be tailor-made for target applications. For example, metal-organic frameworks (MOF) are a notable class of molecular materials made by growing scaffold-like crystalline structures containing metallic ions and organic molecules. Some envisioned optical applications of MOFs are enhancement of luminescence, second harmonic generation, Raman scattering, and infrared sensing.
For the full realization of their potential, the spectacular advances in fabrication techniques need to be matched by accurate and computationally efficient theoretical models. Such models should, on the one hand, underpin the computer-aided design of new materials aiming at substituting costly experimental comparisons of different alternatives. On the other hand, the theoretical tools should support the analysis and interpretation of experimental data. The multi-scale and multi-disciplinary characters of the problem makes the theory challenging. Physics and chemistry are intertwined together across spatial scales ranging from nanometers to centimeters. For example, there is a huge scale gap between the molecular unit cells of a MOF scaffold (~ 1 nanometer), and macroscopic systems such as MOF films that are hundreds of nanometers in each dimension. Additional complexity is added when the materials are placed inside an optical cavity for enhancing a particular light-matter interaction effect. The cavity modes are yet another degree of freedom amenable to optimization beyond Fabry-Perot configurations, and, when the interaction is strong enough, hybrid light-matter modes known as polaritons will form inside the cavity: The optical properties of the joint system can differ significantly from the separate responses of cavity and materials.
In my talk, I will explain a new approach [1] to rigorously compute the joint optical response of molecular materials inside cavities. Using a recent connection between quantum-chemistry and Maxwell scattering theory [2], the output of ab initio DFT and TD-DFT calculations can be fueled into Maxwell solvers. When the molecules are either spatially disordered or forming a periodic arrangement, the response and modes of the joint molecules+cavity system can be very efficiently computed using a T-matrix based algorithm [3]. I will show how this approach allows a refined interpretation of recent experimental measurements involving strong light-matter coupling of a MOF inside a Fabry-Perot cavity [4]. We are convinced that our approach will be a very useful tool for the design and verification of the optical properties of new molecular materials.
[1] B. Zerulla, M. Krstic, D. Beutel, C. Holzer, C. Wöll, C. Rockstuhl, and I. Fernandez-Corbaton. "Computing the joint optical response of molecular materials inside optical cavities", In preparation.
[2] I. Fernandez-Corbaton, D. Beutel, C. Rockstuhl, A. Pausch, and W. Klopper. "Computation of Electromagnetic Properties of Molecular Ensembles", ChemPhysChem, 21, 9, 878 (2020)
[3] D. Beutel, A. Groner, C. Rockstuhl, and I. Fernandez-Corbaton, "Efficient simulation of biperiodic, layered structures based on the T-matrix method", J. Opt. Soc. Am. B, 38, 6, 1782-1791 (2021)
[4] R. Haldar, Z. Fu, R. Joseph, D. Herrero,L. Martı́n-Gomis, B.S. Richards, I. A. Howard, A. Sastre-Santos and C. Wöll. "Guest-responsive polaritons in a porous framework: chromophoric sponges in optical QED cavities", Chem. Sci., 2020, 11, 7972.
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