Regensburg 2019 – wissenschaftliches Programm
DY 51.4: Poster
Donnerstag, 4. April 2019, 15:00–18:00, Poster B2
Finite temperature structure of Hybrid Perovskites from ab-initio and classical MD — •Jonathan Lahnsteiner1, Georg Kresse1, Jurn Heinen2, and Menno Bokdam1 — 1University of Vienna — 2University of Amsterdam
Determining the finite temperature structure of the hybrid perovskite MAPbI3 is a challenge for both experimental and theoretical methods. A very powerful computational method that can resolve the atomic structure is molecular dynamics (MD). The resulting structure depends on the density functional approximation (DFA) in the case of ab-initio MD and the force field in classical MD. We compare the structure between 250 K and 400 K obtained with different DFAs and force fields in one consistent manner. In a previous study, we observed a low level of a dynamic correlation between MA molecules in large scale PBEsol MD calculations. Therefore the relative ordering of the neighboring organic molecules as well as the symmetry of the PbI3 framework is analyzed. The distribution function of the molecules is used to map out an effective energy surface for the rotation of a single molecule. This surface is accurately modeled by a pair of cubic harmonics. Available experimental data in literature are compared to the structure obtained with the different methods. The spread in these data is still too large to uniquely determine the method that *best* describes the perovskite, however promising candidates and outliers have been identified. In agreement with our previous benchmarking study based on RPA perturbation theory calculations , we find the SCAN functional is the most likely choice for the MD calculations of the hybrid perovskite.