Levich Institute Seminar Announcement, 12/05/2017
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Nicolas Giovambattista
"Understanding Water Liquid/Glass Polymorphism using the Potential Energy Landscape Approach"
The potential energy landscape (PEL) formalism is a valuable approach within statistical mechanics for describing supercooled liquids and glasses. We use the PEL formalism and computer simulations to study the transformation between low-density (LDL) and high-density liquid (HDL) water, and between low-density (LDA) and high-density amorphous ice (HDA). We employ the ST2 water model that exhibits a LDL-HDL first-order phase transition and a sharp LDA-HDA transformation, as observed in experiments. Our results are consistent with the view that LDA and HDA configurations are associated with two distinct regions (megabasins) of the PEL that are separated by a potential energy barrier. At higher temperature, we find that LDL configurations are located in the same megabasin as LDA, and that HDL configurations are located in the same megabasin as HDA. We show that the pressure-induced LDL-HDL and LDA-HDA transformations occur along paths that interconnect these two megabasins, but that the path followed by the liquid and the amorphous ice differ. We also study the liquid-to-ice-VII first-order phase transition. The PEL properties across this transition are qualitatively similar to the changes found during the LDA-HDA transformation, supporting the interpretation that the LDA-HDA transformation is a “first-order phase” transition between “out-of-equilibrium states”.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
MOST RECENT RESEARCH INTERESTS
I use computer simulations and theory (statistical mechanics, thermodynamics) to study liquids and glasses and related systems, such as nanoparticle systems in solutions. My research is driven both by applications and fundamental questions. Application-driven research topics include the characterization of liquids at interfaces and in nanoscale confinement, and the study of solvent-induced interactions (e.g., hydrophobic interactions). Research projects driven by fun- damental questions include the understanding of glass polymorphism, i.e., the study of materials that can form more than one amorphous solid state (e.g., water), how liquids can be trapped in glassy states (glass transition), and the stabilization of biomolecules (e.g., cryopreservation). I am particularly interested in the properties of water and aqueous solutions.