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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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       Theory of Charge Doping of PbSe Nanocrystals and Nanowires 
                using Surface Adsorbates and Defects

                          Alex Kutana
             Center for Computational Materials Science 
              Naval Research Laboratory, Washington DC

In my talk, I will present a theoretical study of charge doping of
nanocrystalline PbSe nanowires. In particular, I will focus on self-doping of
semiconducting PbSe nanowires via surface vacancies and surface adatoms. I
will report the results of electronic structure calculations of the ground
state properties and band structures of PbSe nanowires of various sizes and
with various surface defects. While the ground state properties of nanowires
are predicted well by semilocal density functionals within the density
functional theory, these functionals fail at predicting the correct band
structure. The failures will be addressed in an illustrative example comparing
the band structures obtained using semilocal density functionals with those
from hybrid functionals as well as the GW method. I will show that the
improvements afforded by hybrid functionals and the GW method over semilocal
functionals are significant and comparable to those observed in isolated
molecules and three-dimensional crystals.

                      Monday, March 28, 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