Laforge, C.Passerone, DanieleHarris, A. BrooksLambin, PhilippeTosatti, Erio2023-05-232023-05-232001-08-202015-08-13https://repository.upenn.edu/handle/20.500.14332/43186We propose a two-stage mechanism for the rotational surface disordering phase transition of a molecular crystal, as realized in C60 fullerite. Our study, based on Monte Carlo simulations, uncovers the existence of a new intermediate regime, between a low-temperature ordered (2×2) state, and a high-temperature (1×1) disordered phase. In the intermediate regime there is partial disorder, strongest for a subset of particularly frustrated surface molecules. These concepts and calculations provide a coherent understanding of experimental observations, with possible extension to other molecular crystal surfaces.PhysicsArticle