We show that the energy functional of ensemble Density Functional Theory (DFT) [Perdew et al., Phys. Rev. Lett. 49, 1691 (1982)] in systems with attractive interactions is a convex function of the fractional particle number N and is given by a series of straight lines joining a subset of ground-state energies. As a consequence the exchange-correlation (XC) potential is not discontinuous for all N. We highlight the importance of this exact result in the ensemble-DFT description of the negative-U Anderson model. In the atomic limit the discontinuity of the XC potential is missing for odd N while for finite hybridizations the discontinuity at even N is broadened. We demonstrate that the inclusion of these properties in any approximate XC potential is crucial to reproduce the characteristic signatures of the charge-Kondo effect in the conductance and charge susceptibility.

Perfetto, E., Stefanucci, G. (2012). Missing derivative discontinuity of the exchange-correlation energy for attractive interactions: the charge Kondo effect. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 86(8) [10.1103/PhysRevB.86.081409].

Missing derivative discontinuity of the exchange-correlation energy for attractive interactions: the charge Kondo effect

Perfetto, E;STEFANUCCI, GIANLUCA
2012-01-01

Abstract

We show that the energy functional of ensemble Density Functional Theory (DFT) [Perdew et al., Phys. Rev. Lett. 49, 1691 (1982)] in systems with attractive interactions is a convex function of the fractional particle number N and is given by a series of straight lines joining a subset of ground-state energies. As a consequence the exchange-correlation (XC) potential is not discontinuous for all N. We highlight the importance of this exact result in the ensemble-DFT description of the negative-U Anderson model. In the atomic limit the discontinuity of the XC potential is missing for odd N while for finite hybridizations the discontinuity at even N is broadened. We demonstrate that the inclusion of these properties in any approximate XC potential is crucial to reproduce the characteristic signatures of the charge-Kondo effect in the conductance and charge susceptibility.
2012
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore FIS/03 - FISICA DELLA MATERIA
English
Con Impact Factor ISI
Perfetto, E., Stefanucci, G. (2012). Missing derivative discontinuity of the exchange-correlation energy for attractive interactions: the charge Kondo effect. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 86(8) [10.1103/PhysRevB.86.081409].
Perfetto, E; Stefanucci, G
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/95100
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