TY - JOUR
KW - ixs
KW - paper
AU - Simo Huotari
AU - Marco Cazzaniga
AU - Hans-Christian Weissker
AU - Tuomas Pylkkänen
AU - Harald Müller
AU - Lucia Reining
AU - G Onida
AU - Giulio Monaco
AB - We present the dynamic structure factor S(Q,ω) of Na valence electrons in the range of momentum transfer 0.5kF < Q < 2.4kF and energy transfer 3 eV < ω < 30 eV determined by inelastic x-ray scattering spectroscopy. In this range, we observe how the collective plasmon excitations decay into the single-particle excitation continuum. We compare the results to calculations using time-dependent density-functional theory with different approximations. The failure of both random-phase approximation and time-dependent local-density approximation (TDLDA) is shown to become important at kF < Q < 2.4kF , while TDLDA with an additional inclusion of quasiparticle lifetime effects reproduces the experimental spectra well. The experimental valenceelectron response reaches the single-particle spectrum surprisingly early, at Q ≈ 1.5kF . This is manifested both in the spectral shape and the peak dispersion. The experimental spectra are nearly free of any fine structure, confirming that the peak-shoulder structure observed in many other materials is due to band-structure effects, which turn out to be negligible in Na.
BT - Phys. Rev. B
DA - Aug
DO - 10.1103/PhysRevB.84.075108
N2 - We present the dynamic structure factor S(Q,ω) of Na valence electrons in the range of momentum transfer 0.5kF < Q < 2.4kF and energy transfer 3 eV < ω < 30 eV determined by inelastic x-ray scattering spectroscopy. In this range, we observe how the collective plasmon excitations decay into the single-particle excitation continuum. We compare the results to calculations using time-dependent density-functional theory with different approximations. The failure of both random-phase approximation and time-dependent local-density approximation (TDLDA) is shown to become important at kF < Q < 2.4kF , while TDLDA with an additional inclusion of quasiparticle lifetime effects reproduces the experimental spectra well. The experimental valenceelectron response reaches the single-particle spectrum surprisingly early, at Q ≈ 1.5kF . This is manifested both in the spectral shape and the peak dispersion. The experimental spectra are nearly free of any fine structure, confirming that the peak-shoulder structure observed in many other materials is due to band-structure effects, which turn out to be negligible in Na.
PB - American Physical Society
PY - 2011
EP - 075108
T2 - Phys. Rev. B
TI - Dynamical response function in sodium studied by inelastic x-ray scattering spectroscopy
UR - http://link.aps.org/doi/10.1103/PhysRevB.84.075108
VL - 84
ER -