Institute for Theoretical Condensed Matter physics (TKM)

Broadening of the derivative discontinuity in density functional theory

  • Author:

    F. Evers and P. Schmitteckert

  • Source:

    Phys. Chem. Chem. Phys. 13, 14417-14420 (2011)

  • Date: 2011
  • We clarify an important aspect of density functional theories, the broadening of the derivative discontinuity (DD) in a quantum system, with fluctuating particle number. Our focus is on a correlated model system, the single level quantum dot in the regime of the Coulomb blockade. We find that the DD-broadening is controlled by the small parameter Γ/U, where Γ is the level broadening due to contacting and U is a measure of the charging energy. Our analysis suggests that Kondoesque fluctuations have a tendency to increase the DD-broadening in our model by a factor of two.