Rebecca Nicholls1
University of Oxford1
Recent advances in hardware mean we can now probe phonon vibrations in an electron microscope, giving us access to spectra with previously unprecedented spatial resolution and having the benefit of atomically resolved chemical analysis within the same instrument. Interpreting the spectra containing the signal from phonon vibrations is not always trivial, and simulation can be a vital part of maximising the information extracted from the data. There are several different theoretical approaches to simulating spectra, and this presentation will focus on modelling spectra from first principles. I will first discuss why spectra obtained in different experimental geometries (impact and aloof modes) require different theoretical approaches. I will then show how first principles calculations can be used to describe spectra taken in the aloof regime from molecular crystals and that it is possible to distinguish between different crystal polymorphs of the same molecule.