Ensemble density-functional theory for excited states : exact exchange-correlation energies in a model system

CTMM
Date: 2017-04-28 10:00

Lieu: Salle Réunion CTMM Bât15 RdC

Ensemble density-functional theory (eDFT) [1] is a time-independent alternative to time-

dependent DFT for the calculation of excitation energies. In this context, the basic variable

becomes the ensemble density which is a weighted sum of ground- and excited-state densi-

ties. Even though eDFT is appealing, in particular because it provides an explicit description of

multiple electronic excitations and it allows for rigorous combinations with multiconfiguratio-

nal wavefunction-based methods [2,3,4], it is not routinely used nowadays. This is essentially

due to the lack of approximate (weight-dependent) functionals for ensembles. In this talk I will

present a generalized adiabatic connection formalism for ensembles (GACE) [5] which enables

to construct, in principle exactly, the ensemble exchange-correlation (xc) functional from the

conventional ground-state one. Exact results will be presented for the nontrivial asymmetric

Hubbard dimer [6]. The weight-dependence of the ensemble xc functional will be discussed in

various correlation regimes. In particular, it will be shown that in some cases the ground-state

xc functional is a good approximation to the ensemble one.

[1] E. K. U. Gross, L. N. Oliveira, and W. Kohn, Phys. Rev. A 37, 2809 (1988).

[2] B. Senjean, S. Knecht, H. J. Aa. Jensen, and E. Fromager, Phys. Rev. A 92, 012518 (2015).

[3] B. Senjean, E. D. Hedegaard, M. M. Alam, S. Knecht, and E. Fromager, Mol. Phys. 114, 968 (2016).

[4] Md. M. Alam, S. Knecht, and E. Fromager, Phys. Rev. A 94, 012511 (2016).

[5] O. Franck and E. Fromager, Mol. Phys. 112, 1684 (2014).

[6] K. Deur, L. Mazouin, and E. Fromager, Phys. Rev. B 95, 035120 (2017).

 

 

 

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  • 2017-04-28 10:00

Propulsé par iCagenda

Institut Charles Gerhardt Montpellier - Direction

UMR 5253 - CNRS/UM/ENSCM
  • Université de Montpellier
  • Place Eugène Bataillon
  • CC 1700 - Bâtiment 17 -1er étage
  • Tel: +33 (0)4 67 14 93 50
  • Email: direction@icgm.fr
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