--------------------------------------------------------------------
           COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
                              College of Science
                       (CDS Department CSI 898-Sec 001)
--------------------------------------------------------------------
Phase transitions of films and adsorbed gases caused by the structure 
                      and relaxation of the substrate

                             Silvina Gatica
Department of Physics and Astronomy, Howard University, Washington D.C.

Gases adsorbed in porous materials form phases usually commensurate 
with the substrate. Very small changes in the structure of the 
substrate can have dramatic consequences in the properties and phases 
of the adsorbate. Large qualitative effects are found for several systems, 
for which substrate relaxation may not be neglected. One application is 
a determination of the ground state of 3He in slit and cylindrical pores. 
Because of the relaxation of the substrate, there results a much stronger 
cohesion than would be found for a rigid host. Similar increased binding 
effects of relaxation are found for classical fluids confined within slit 
pores or nanotube bundles. These effects include large changes of the 
critical temperature (slit pore and nanotube bundle substrates) and 
condensation of the quasi-one dimensional fluid (carbon nanotube substrate).  
Another interesting phase transition we will discuss is an ordering 
transition of a film adsorbed on top of a monolayer of C60 molecules. 
Both the lattice constant and the corrugation are larger than the typical 
of most traditional surfaces. These differences give rise to new phenomena, 
such as unusual commensurate phases.  The transition is investigated with 
Monte Carlo simulations and analytical (lattice-gas) models. 

                        Monday, February 9, 2009
                                  4:30 pm
                     Room 301, Research I, Fairfax Campus

Refreshments will be served at 4:15 PM.
----------------------------------------------------------------------
Find the schedule at www.cmasc.gmu.edu/seminar/schedule.html
--------------------------------------------------------------------