In the optical spectroscopy of solids, the interaction between bound electron-hole pairs (excitons) and lattice vibrations (phonons) plays a fundamental role in the interpretation of many experimentally relevant quantities, like the shape of optical spectra and peak linewidths. Yet, its theoretical modelling is difficult.
This project is about the ab initio, parameter-free numerical description of the microscopic origin of exciton-phonon coupling in two prototypical Van-der-Waals layered materials: bilayer tungsten disulphide (WS2) and bulk rhombohedral boron nitride (rBN).
These systems are technologically relevant because of their capability of efficiently emitting light in the visible and UV range.
In order to carry the project out, highly predictive state-of-the-art methods for the numerical investigation of optical and vibrational properties will be combined together: such methods are very demanding from a computational perspective and require consistent HPC resources to be properly applied.
In particular, we will use two different flagship codes of the EU MaX “Materials Science at the Exascale” Centre of Excellence (http://www.max-centre.eu/). We will obtain new observables that go beyond the scope of current methods, namely phonon-assisted excitonic optical spectra, explaining their fine structure in the case of WS2 and rBN, as well as expanding the theoretical reach of parameter-free optical spectroscopy.