TIME DEPENDENT DENSITY FUNCTIONAL THEORY ... - TDDFT.org

An iterative GW approach for the (111)
surface of diamond
Margherita Marsili
Università di Roma Tor Vergata
The Pandey Chain model seems to be the most stable reconstruction for the (111) surface
of diamond, being the atoms on the chain neither buckled nor dimerized. Experimental data
confirm the absence of dimerization but cannot exclude the presence of buckling. Within DFT the
electronic band structure related to the fully relaxed structure appears semimetallic in contrast
with experiments which show a gap of at least 0.5 eV. This could be due to a wrong equilibrium
geometry in the calculations or to the usual DFT band gap problem. Introducing quasiparticle
corrections within a self-consistent GW scheme, using an iterative procedure for updating the
quasiparticle energies, we found for this surface an electronic gap close to 1 eV. Preliminary results
on the optical properties are also presented and discussed.
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