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     COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
   AND THE SCHOOL OF PHYSICS, ASTRONOMY AND COMPUTATIONAL SCIENCES
                       (CSI 898-Sec 001)
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      Predicting Structure and Reactivity at Metal Oxide Surfaces 
                     in Complex Environments

                           Anne M. Chaka
    Physics Laboratory, National Institute of Standards and Technology

Metal oxide surfaces and nanoparticles play an important role in contaminant
sequestration and speciation in groundwater aquifers and soils, as well as a
wide range of technological applications such as catalysis, microelectronics,
gas sensors, and corrosion protection. The behavior and structure of these
surfaces towards reactive species is dependent upon complex environmental
factors as well as the electronic structure of the oxide. Unfortunately the
gap between conditions accessible to UHV surface science and what is observed
in nature or in industry has made it difficult to understand why, for example,
the (0001) surfaces of isostructural hematite (a-Fe2O3) and alumina (a-Al2O3)
exhibit very different absorption strengths of heavy metal contaminants such
as Pb in aqueous systems, while the (1-102) surfaces exhibit almost identical
reactivity. Theoretical predictions and modeling provide a powerful means to
evaluate fundamental chemical processes with atomic resolution, but also face
the challenge of including the effects of a complex environment.  The method
of ab initio thermodynamics makes it possible to link 0K density functional
theory electronic structure and vibrational calculations to finite
temperatures and pressures. This method enables calculation of the free energy
of a surface or nanoparticle in equilibrium with multiple species in
heterogeneous systems, as well as determining how structure, reactivity,
electronic, and magnetic properties change in response to the environment. 

                     Monday, October 3, 2011
                               4:30 pm
                    Room 301, Research I, Fairfax Campus

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