Athanassios Z. Panagiotopoulos: Research Projects

Research in the group focuses on development and application of theoretical and computer simulation techniques for the study of properties of fluids and materials. Emphasis is on molecular-based models that explicitly represent the main interactions in a system. These models can be used to predict the behavior of materials at conditions inaccessible to experiment and to gain a fundamental understanding of the microscopic basis for observed macroscopic properties. A major component of our work requires large-scale numerical calculations using a number of powerful molecular simulation methodologies, many of which have been developed in our group. An example of such a methodology is Gibbs ensemble Monte Carlo, which provides a direct way to obtain coexistence properties of fluids from a single simulation. Areas of current interest are:

Self-assembly in Surfactant, Polyelectrolyte and Polyampholyte Solutions

We are interested in investigating the basic mechanism of self-assembly in surfactant solutions. We have studied the formation of micelles by simple models of non-ionic surfactants using a lattice model. We have developed computational methodologies for accurate determination of critical micelle concentrations (cmc's) for systems that aggregate at low surfactant loadings. Our continuing work in this area focuses on the behavior of mixed surfactant systems and ionic amphiphiles. An additional area of interest is conformational transitions and self-assembly of polyelectrolyte and polyampholyte chains.

Phase Transitions of Ionic Systems

We are investigating phase transitions in simple models for ionic melts and solutions. These systems are extremely difficult to handle by either theoretical or numerical methods because of the presence of infinite-range ionic forces and strong counterion association.  Work by our group and others (reviewed here) has generated estimates for the phase behavior of  "primitive models" for ionic systems consisting of charged hard spheres in a dielectric continuum. Our recent work has extended the charge asymmetry to ratios of 2000:1, appropriate for charged colloids.

 


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Last updated: Nov. 2007