Center for Functional Nanomaterials Seminar

Fluid-solid phase transitions in colloidal and atomistic systems with long and short range interparticle interactions are important in various modern fabrication processes with applications in supercomputing, characterization of proteins and nano/micro devices. We explore classical density functional theory (DFT) as a tool for making predictions of freezing transitions in colloidal and atomistic systems.
Specifically we develop a novel DFT formulation that employs a closure relation in the form of a bridge functional to sum the higher order terms in the free energy expansion. The bridge functional for freezing transitions is qualitatively and quantitatively different from conventional closures like hypernetted-chain and Percus-Yevick, which are known to give good results in inhomogeneous liquid states. We develop a highly accurate representation of the bridge functional for commonly employed colloidal and atomistic potentials such as hard spheres, inverse power repulsions and Lennard-Jones interactions. The results show that there is universality in the bridge functional across these different potentials, which is promising for the development of widely applicable closures at freezing transitions. The findings presents a new understanding of closure relations in the free energy expansions and the results can be used to design a novel classical DFT tool for high accuracy and low cost predictions of fluid-solid phase diagrams from knowledge of interaction potentials.