Long-range contribution to the exchange-correlation kernel of time-dependent density functional theory

Phys. Rev. B 69, 155112 – Published 23 April 2004
Silvana Botti, Francesco Sottile, Nathalie Vast, Valerio Olevano, Lucia Reining, Hans-Christian Weissker, Angel Rubio, Giovanni Onida, Rodolfo Del Sole, and R. W. Godby

Abstract

We discuss the effects of a static long-range contribution -α/q2 to the exchange-correlation kernel fxc(q) of time-dependent density functional theory. We show that the optical absorption spectrum of solids exhibiting a strong continuum excitonic effect is considerably improved with respect to calculations where the adiabatic local-density approximation is used. We discuss the limitations of this simple approach, and in particular that the same improvement cannot be found for the whole spectral range including the valence plasmons and bound excitons. On the other hand, we also show that within the range of validity of the method, the parameter α depends linearly on the inverse of the dielectric constant, and we demonstrate that this fact can be used to predict continuum excitonic effects in semiconductors. Results are shown for the real and imaginary part of the dielectric function of Si, GaAs, AlAs, diamond, MgO, SiC and Ge, and for the loss function of Si.

DOI: http://dx.doi.org/10.1103/PhysRevB.69.155112

  • Received 1 December 2003
  • Revised 6 February 2004
  • Published 23 April 2004

© 2004 The American Physical Society

Authors & Affiliations

Silvana Botti, Francesco Sottile, Nathalie Vast, Valerio Olevano, and Lucia Reining

  • Laboratoire des Solides Irradiés, CNRS-CEA, École Polytechnique, F-91128 Palaiseau, France

Hans-Christian Weissker

  • Institut für Festkörpertheorie und Theoretische Optik, Friedrich-Schiller-Universität, D-07743 Jena, Germany

Angel Rubio

  • Departamento de Física de Materiales, Facultad de Ciencias Químicas, Universidad del Pais Vasco, Donostia International Physics Center (DIPC) and Centro Mixto CSIC-UPV/EHU, Donostia, E-20018 San Sebastián, Basque Country, Spain

Giovanni Onida

  • Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica dell’Università di Milano, via Celoria 16, I-20133 Milano, Italy

Rodolfo Del Sole

  • Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica dell’Università di Roma “Tor Vergata,” via della Ricerca Scientifica, I-00133 Roma, Italy

R. W. Godby

  • Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom

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