Abstract
The role of localized $d$-bands in the dynamical response of Cu is investigated, on the basis of {\em ab initio} pseudopotential calculations. The density-response function is evaluated in both the random-phase approximation (RPA) and a time-dependent local-density functional approximation (TDLDA). Our results indicate that in addition to providing a polarizable background which lowers the free-electron plasma frequency, d-electrons are responsible, at higher energies and small momenta, for a double-peak structure in the dynamical structure factor. These results are in agreement with the experimentally determined optical response of copper. We also analyze the dependence of dynamical scattering cross sections on the momentum transfer.
Highlights
Our results indicate that in addition to providing a polarizable background which lowers the free-electron plasma frequency, d electrons are responsible, at higher energies and small momenta, for a double-peak structure in the dynamical structure factor
Silver is one of the best understood systems, where the free-electron plasma frequency is strongly renormalizedred-shiftedby the presence of a polarizable background of d electrons.[1]
Copper presents no decoupling between s p and d orbitals, and a combined description of these one-electron states is needed to address both structural and electronic properties of this material
Summary
Our results indicate that in addition to providing a polarizable background which lowers the free-electron plasma frequency, d electrons are responsible, at higher energies and small momenta, for a double-peak structure in the dynamical structure factor These results are in agreement with the experimentally determined optical response of copper. Though in the case of other materials, such as semiconductors, electron-hole interactionsexcitonic renormalizationstrongly modify the single-particle optical absorption profile,[2] metals offer a valuable playground for investigations of dynamical exchange-correlation effects of interacting many-electron systems within a quasiparticle picture.[3] ab initio calculations of the dynamical response of a variety of simple metals, as obtained within the random-phase approximationRPA, successfully account for the experimentally determined plasmon dispersion relations[4] and scattering cross sections.[5] Within the same many-body framework, ab initio calculations of the electronic stopping power of real solids have been reported.[6]. The wave vector q is in the first Brillouin zoneBZ, G and GЈ are reciprocal lattice vectors, vG(q)ϭ4/͉qϩG2 are the Fourier coefficients of the bare Coulomb potential, 0163-1829/99/59͑19͒/12188͑4͒/$15.00
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