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Excitons -- correlated electron-hole pairs generated upon photoexcitation -- provide a fundamental framework for describing the low-energy optical excitations in semiconductors and insulators. With continued advances in powerful spectroscopic techniques, we are increasingly able to probe how excitons interact with their environment, especially their coupling to lattice vibrations.

In this seminar, I will present our recent efforts to develop and apply ab-initio methods, grounded in many-body perturbation theory, to study exciton-phonon interactions in complex materials. I will begin by discussing various ways in which phonons can couple to excitons, detailing how phonons renormalize exciton binding energies in halide perovskites and influence exciton line shapes in two-dimensional transition metal dichalcogenides.

Motivated by the inherent complexity of modeling coupled exciton–phonon systems, the second part of the talk will introduce our recent work on Maximally Localized Exciton Wannier Functions (MLXWFs). This new formalism provides a compact, real-space representation of exciton states, offering insights into exciton band dispersion and  topology and paving the way for to scalable modeling of exciton dynamics. I will demonstrate the utility of this framework through a detailed case study on how lattice vibrations influence exciton transport in organic semiconductors—highlighting how MLXWFs can help tackle the next generation of exciton–phonon problems.