Kondo effect in the Kohn-Sham conductance of multiple levels quantum dots

Physica Status Solidi B 250, 2378 (2013)

Kondo effect in the Kohn-Sham conductance of multiple levels quantum dots

G. Stefanucci, S. Kurth

At zero temperature, the Landauer formalism combined with static density functional theory is able to correctly reproduce the Kondo plateau in the conductance of the Anderson impurity model provided that an exchange- correlation potential is used which correctly exhibits steps at integer occupation. Here we extend this recent finding to multi-level quan- tum dots described by the constant-interaction model. We derive the exact exchange-correlation potential in this model for the isolated dot and deduce an accurate approximation for the case when the dot is weakly cou- pled to two leads. We show that at zero temperature and for non-degenerate levels in the dot we correctly obtain the conductance plateau for any odd number of electrons on the dot. We also analyze the case when some of the levels of the dot are degenerate and again obtain good qualitative agreement with results obtained with alterna- tive methods. As in the case of a single level, for temperatures larger than the Kondo temperature, the Kohn-Sham conduc- tance fails to reproduce the typical Coulomb block- ade peaks. This is attributed to dynamical exchange- correlation corrections to the conductance originating from time-dependent density functional theory.

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