We observe using ab initio methods that localized surface plasmon resonances in icosahedral silver nanoparticles enter the asymptotic region already between diameters of 1 and 2 nm, converging close to the classical quasistatic limit around 3.4 eV. We base the observation on time-dependent density-functional theory simulations of the icosahedral silver clusters ${\mathrm{Ag}}_{55}\left(1.06\mathrm{nm}\right)$, ${\mathrm{Ag}}_{147}\left(1.60\mathrm{nm}\right)$, ${\mathrm{Ag}}_{309}\left(2.14\mathrm{nm}\right)$, and ${\mathrm{Ag}}_{561}(2.68 \mathrm{nm})$. The simulation method combines the adiabatic GLLB–SC exchange-correlation functional with real time propagation in an atomic orbital basis set using the projector-augmented wave method. The method has been implemented for the electron structure code GPAW within the scope of this work. We obtain good agreement with experimental data and modeled results, including photoemission and plasmon resonance. Moreover, we can extrapolate the ab initio results to the classical quasistatically modeled icosahedral clusters.

• Received 12 August 2014
• Revised 4 March 2015

DOI:https://doi.org/10.1103/PhysRevB.91.115431