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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS        
                   School of Computational Sciences	
                           (CSI 898-Sec 001) 
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             Ab initio molecular-dynamics studies of phase 
                transitions in ionic molecular solids.

                         M. M. Ossowski
Center for Computational Materials Science, Naval Research Laboratory,
                         Washington D. C. 

We have developed and applied a parameter-free molecular-dynamics (MD) method
based on inter-ionic pair potentials obtained through the Gordon-Kim modified
electron gas formalism extended to molecular ions.  This very fast MD scheme
has allowed us to examine microscopically various supercells of crystals as
we have stepped them through order-disorder as well as structural phase
transitions.  As an illustration I will discuss our recent results for a
class of solids with linear molecular ions which includes azides, cyanates
and thiocyanates.   We will see how the unlocking of the rotational motion of
these ions drives the structural transformations and how we make predictions
about high-temperature phases in these systems.

                         Monday , November 12, 2001
                                  4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served at 4:15 PM.
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Find the schedule at http://www.csi.gmu.edu/lcdm/seminar/schedule.html