Figure 2: The dipole moment and charge density oscillations.
From: Interplay between plasmon and single-particle excitations in a metal nanocluster
(a) The dipole moment oscillations as a function of time. (b) The charge density difference Δρ when the dipole moment achieves a local maximum or local minimum as labelled in a. At t=19.2 and 19.8 fs, the dipole moment oscillation amplitude is large. The Δρ is localized on the surface, and sloshes from one side of the nanocluster to the other side, fitting well with the classical picture of the surface plasmon mode. When the dipole moment oscillation is decayed (t=38.0 and 38.6 fs), the charge sloshing disappears, and Δρ is no longer localized on the surface.
