Development of Coarse-Grained Models for Glass Forming Liquids

A long-standing problem in condensed matter physics is the establishment of a mechanism for super-Arrhenian mobility behavior of glass forming materials, where molecular simulations can provide significant insight. All atom potentials are useful, but coarse-grained potentials offer the possibility of both faster simulations and the ability to create new molecules that can probe various postulates that underlie the cause of super-Arrhenian behavior. Coarse-grained potentials have been prepared using the iterated Boltzmann inversion technique, where real glass forming molecules are used as the target system. These potentials produce systems which stabilize the crystalline, liquid, and supercooled liquid phase, which are necessary components the excess quantities that have been postulated to control the mobility in the supercooled region. Determination of thermodynamic quantities in the crystal can be polluted by pre-melting; thus, a new method of extracting and extrapolating the crystalline energy has been developed. Using the coarse-grained potentials along with the improved methods of determining excess quantities, the connection between mobility in the super-cooled region and relevant excess quantities is investigated.