# Regensburg 2004 – wissenschaftliches Programm

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# O: Oberflächenphysik

## O 37: Zeitaufgelöste Spektroskopie I

### O 37.5: Vortrag

### Donnerstag, 11. März 2004, 16:45–17:00, H36

**Treatment of many-body effects in sodium clusters by means of GW theory** — •Yaroslav Pavlyukh and Wolfgang Hübner — FB Physik, TU Kaiserslautern, D-67663 Kaiserslautern, Germany

The GW approximation for the calculation of electronic properties of
systems without translational invariance like clusters or molecules is
presented. In our implementation of the GW approximation we use the
expansion of all quantities in gaussian type basis functions. The Green
function, screened interaction, and self-energy are represented on the real
axis of the frequency domain. The dielectric function is treated without
any simplifications, such as the plasmon pole approximation. Convolutions
are performed using fast Fourier transforms to the real time and back. We
apply our approach to the range of Na_{n} clusters (n=9-25). We present
ionization potentials, electron affinities, band-gaps, plasmon energies,
and life-times of quasiparticle states and collective excitations, which
shows exellent agreement with experiments and other theories, such as
TDLDA. A partially self-consistent GW calculation on Na_{9}^{+} cluster
enables us to improve the HOMO-LUMO gap (4.5 eV – HF, 3.7 eV –
G_{0}W_{0}, 3.37 eV GW) and to determine the plasmon width and lifetime (2
eV and 4.1 fs, respectively).