TDDFT for non-equilibrium strongly correlated models: Fundamental theorem
Wednesday, 30 November 2011, 13:30
We formulate a discrete version of time-dependent DFT well suited
to study model systems and we then apply it to the Anderson model.
We show that the derivative discontinuity of the exchange-correlation density
functional is intimately related to the Coulomb blockade phenomenon.
To include the discontinuity we propose an approximate functional based
on finite-temperature DFT. This functional
yields the exact Kohn-Sham potential at the particle-hole symmetric point
and exhibits a derivative discontinuity in the limit of zero temperature.
We then use it to study the zero-temperature conductance within the
standard Landauer formalism and show that the Kondo plateau is accurately reproduced.
On the other hand, at the Kondo temperature the exact Kohn-Sham
conductance overestimates the exact one by an order of magnitude. To
understand the failure of DFT we resort to its time-dependent version and
conclude that the suppression of the Kondo resonance with increasing temperature
must be attributed to dynamical exchange-correlation corrections.