------------------------------------------------------------------------
    COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS
        Institute for Computational Sciences and Informatics
                              CSI 898-Sec 001  
------------------------------------------------------------------------
Free Energy Predictions in Aqueous Solutions and Quasi-2-Dimensional Systems

                             Joe Slusher
                Physical and Chemical Properties Div.
                 Nat'l. Inst. of Stand's. and Tech.
                      Gaithersburg, MD 20899

In order to be useful for predictive or even interpretative roles,
molecular simulation must be able to accurately reproduce measureable
thermophysical properties, while retaining (for the sake of efficiency)
as much simplicity as possible in the models.
Of these thermophysical properties, one of the most important in both
industrial chemical process design and in biological science is the 
Gibbs free energy in a solution.  Numerous approaches have been developed  
to calculate the latter, but model validation by comparison with experiment 
can be hampered by the fact that these methods may incorporate systematic
errors (due, e.g., to system-size effects) or large statistical uncertainties. 
The present work illustrates a molecular dynamics (MD) method, based on the
Kirkwood coupling parameter approach, with which very precise free energy 
calculations have been obtained.  I examine several example aqueous systems,
modelled using classical molecular dynamics and simple, non-polarizable models.
Particular emphasis is given to the sensitivity of the results to the
empirically derived (Lorentz-Berthelot) mixture parameters.

We have also been developing a quasi-2-dimensional MD model designed to 
investigate the retention mechanism in reversed-phase liquid chromatography. 
Results from this work will also be presented.

                         Monday , September 21 1998
                                 4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served.
--------------------------------------------------------------------------
(http://www.csi.gmu.edu/lcdm/seminar/schedule.html)