Research

Our current research includes:

First-principles Monte Carlo simulations of phase equilibria at extreme conditions. By coupling widely-used Density Functional Theory electronic structure codes to advanced Monte Carlo simulation algorithms, we can obtain liquid-vapor and liquid-liquid coexistence lines at extremes of temperature and pressure not easily accessed by experiment. We are currently working on phase equilibria of atomic systems, such as lithium metal, lithium/sodium mixtures, phosphorous, sulfur, and carbon.

Multiscale simulations of sol-gel materials. Xerogels and aerogels are nanostructured porous materials prepared using sol-gel processes that can display a wide range of chemical, topological and morphological characteristics. They are extensively used in chromatography, catalysis, optics, biotechnology and chemical sensing. The relationship between the complex structures of these materials and their useful properties is poorly understood. We address this by developing realistic models of these materials through a multi-scale approach involving: (1) quantum mechanics, used to understand the interactions between gel precursor species and to parameterize reactive simulation models, (2) molecular simulations, to model the growth and structure of small silica aggregates in solution (the "sol"), and (3) coarse-grained and lattice-type models, to study the large-scale evolution of gel structures and solvent-induced structural changes during gel drying.

Capillary phenomena. The behavior of gases and liquids in nanometer-scale pores is considerably different than in the bulk, and is important in separation technologies, catalytic reactors, lubrication, nano-scale devices, and materials characterization. Using recently developed simulation methods, we can directly probe the dynamics and thermodynamics of these systems. We have done a number of studies of capillary condensation in controlled-pore glasses and sol-gel materials, with a particular focus on the application of capillary phenomena in materials characterization.

We are also interested in the development of new simulation methodologies, high-performance computing and parallel simulation algorithms, and computer graphics visualizations; in this area we are participating in an NSF-supported collaborative project entitled "Cyberinfrastructure for Phase-space Mapping: Free Energies, Phase Equilibria and Transition Paths".

Financial support for our research is listed on our funding page.