Confinement and correlation effects on plasmons in an atom-scale metallic wire

We have studied the effect of confinement and correlations on the plasmon dispersion in an atom-scale metallic wire by determining the electron density response function. The wire electrons are modelled as comprising a quasi-one-dimensional homogeneous gas, with different transverse confinement models. The response function is calculated by including electron correlations beyond the random-phase approximation within the self-consistent mean-field approach of Singwi et al (1968 Phys. Rev. 176 589). The plasmon dispersion results are found to be in very good agreement with the recent electron-energy-loss spectroscopy measurements by Nagao et al (2006 Phys. Rev. Lett. 97 116802). However, our predictions are found to depend strongly on the nature of the confinement model, the structure of the one-dimensional electronic band and the electron effective mass, implying a crucial role for the wire structure.