Development of Coarse-Grained Models for Glass Forming Liquids

Determination of the mechanism for super-Arrhenian behavior of glass forming liquids is one of the unsolved problems in condensed matter physics. Recent developments using experimental data showed the connection between the relaxation time as a function of temperature and pressure, and the excess internal energy which is the difference between internal energy of a liquid and a crystal (Phy. Rev. Mat., 2, 055604, 2018). It would be valuable to explore this connection using simulation. Atomistic molecular models are too complex and thus too slow to cover a sufficiently wide time interval. Simplified models such as binary Lennard-Jones mixtures or Kremer-Grest polymer models do not have a crystalline phase. In this paper we report on the development of molecular models which are simple enough for fast simulations, but that also possess stable super-cooled liquid and crystalline phases. The strategy for obtaining such models is to coarse-grain (CG) atomistic models of known glass formers using the iterated Boltzmann inversion procedure. The resulting two- and three-bead CG models also exist in both the super-cooled liquid and crystalline states. The translational and rotational mobility as well as internal energy have been determined for a several of these new CG models.