PIF2024 - Linear response of INsulators with broken SPace-Inversion or time-REversal symmetries from first principles (PID2023-152710NB-I00)

In the realm of condensed matter physics, the exploration of emerging materials properties has been for many decades the main driving force behind technological advancements. From a theory viewpoint, a central thrust consists in understanding how the internal symmetries of crystals (or the lack thereof) affect their fundamental behavior. Time-reversal (TR) and space- inversion (SI) symmetries dictate the invariance of physical laws under the reversal of time or spatial coordinates. When broken, separately or simultaneously, a rich spectrum of physical phenomena emerges, offering exciting avenue for tailoring materials with new (and potentially useful) functionalities. The primary purpose of this project is to advance our fundamental understanding of how the breakdown of SI and/or TR symmetry manifests itself in the context of optics, acoustics, lattice dynamics and transport. Prime examples thereof include optical and acoustical activity, the thermal Hall conductivity, gyrotropic birefringence and the so-called optical diode effect. Experimental breakthroughs are nowadays reported on a weekly basis, but the underlying theoretical and computational tools to support and guide these discoveries are still scarce. This project is precisely aimed at filling this gap by developing the much-needed know-how, concepts and methodological tools within the framework of first-principles density-functional approaches.