Electronic Correlations and Hubbard Approaches

Tuesday, July 31, 2007 - 11:15am - 12:30pm
EE/CS 3-180
Matteo Cococcioni (University of Minnesota, Twin Cities)
Electronic correlation play a very important role in the
physical properties of many materials characterized by
very localized electronic states (as transition-metals or
rare-earths compounds). Unfortunately, standard approximations
to Density Functional Theory (like the Local Density Approximation
or the Generalized Gradient Approximation) are not accurate enough
to give a proper description of correlation effects.
While multi-configurational Quantum-Chemistry methods are too
expensive for most systems but very small molecules, several corrections
to DFT have been introduced to give a better description of
correlated states without giving up the relatively low computational cost
of DFT calculations. After a general introduction on electronic correlation,
one of the simplest corrective approaches, named LDA+U, will be described
along with its implementation in a plane-wave pseudopotential
DFT code.