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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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First-principles study on a bio-mimetic light-harvesting molecular triad

                         Tunna  Baruah  

          Center for Computational Materials Science
            Naval Research Laboratory, Washington DC

    The properties of a recently synthesized light
harvesting molecular triad containing a porphyrin, carotenoid
and C60 molecule are investigated from  density functional theory. 
In this triad the porphyrin, carotenoid and the C60 act as a 
chromophore, electron donor and acceptor, respectively. This 
molecular triad undergoes a photo-induced charge separation process 
resulting in a large dipole moment.  Our calculations are done using
density-functional theory as implemented in the NRLMOL code to
optimize the triad geometry. We have developed a new ad hoc approach 
to calculate the energies of the excited states within DFT.  We find that
the molecular states are more or less localized on a given component
of the triad and that excitations between the molecular levels can result
in a huge dipole moment.  The transition probabilities between various 
states are calculated and used in a classical  Monte-Carlo simulation 
to estimate the rise time.  Our calculations show the influence of 
local electric fields on the rise time and consequently on the 
application of the molecule in solar-cell technologies.
                       
                      October 17, 4:30 pm
               Room 206, Science & Tech. I, Fairfax Campus

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