Comparison of TDLDA and GW-Bethe-Salpeter Methods for Optical Excitations in Noble Metal Clusters

ORAL

Abstract

We perform a comparative analysis of first principles results for optical spectra of Ag$_n$ and Au$_n$ ($n\le 8$) clusters calculated within the time-dependent local density approximation (TDLDA) and the GW-Bethe-Salpeter (GW-BSE) technique. Both the TDLDA and GW-BSE calculations are performed entirely in real space based on the higher-order finite difference {\em ab initio} pseudopotential method. In the GW-BSE method, the screened Coulomb potential is calculated from the TDLDA polarizability. The convergence of the results with respect to various computational parameters is carefully examined. In general, the TDLDA and GW-BSE methods are in reasonable agreement with respect to peak positions at low energies, while high-energy excitations and oscillator strengths can be different. The GW-BSE results are found to be in a somewhat better agreement with the available experimental data.

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Authors

  • Shing F. Yip

  • Juan-Carlos Idrobo

    • University of Illinois at Chicago

  • Serdar Ogut

    • University of Illinois at Chicago
    • Department of Physics, University of Illinois at Chicago, Chicago IL 60607

  • Murilo Tiago

    • University of Minnesota, Twin Cities
    • University of Minnesota

  • James Chelikowsky

    • University of Texas at Austin
    • University of Texas
    • The University of Texas at Austin
    • Department of Physics and Chemical Engineering, Institute of Computational Engineering and Sciences, University of Texas, Austin, Texas 78712, USA

  • Jinlan Wang

  • Julius Jellinek

    • Chemistry Division, Argonne National Laboratory, Argonne, IL 60439
    • Chemistry Division, Argonne National Laboratory
    • Argonne National Laboratory