An interatomic model potential for molecular dynamics was derived from first–principles and used to study the molecular rotations and relaxation times in methylammonium lead halide, considered the prototypical example of a hybrid crystal with a strong reorientational dynamics. Within the limits of a simple ionic scheme, the potential is able to catch the main qualitative features of the material at zero and finite temperature and opens the way to the development of classical potentials for hybrid perovskites. This work has clarified the temperature dependence of the relaxation times and the interpretation of the experimental data in terms of the different mechanisms contributing to the molecule dynamics.
Contact person: Alessandro Mattoni, IOM–CNR Cagliari