Fig. 4
From: Excited-state vibrational dynamics toward the polaron in methylammonium lead iodide perovskite

Theoretically predicted cluster structures of MAPbI3 perovskite. a Neutral cluster. b Polaron (−1) cluster. c Various perspective comparisons of the neutral (red sphere) and polaron (blue sphere) PbI64− octahedral structures centered in the clusters. The structural comparison shows that the polaron state geometry is more bent and elongated than the neutral, indicated by displacement vectors (green arrows)