Gold Nanowires: A Time-Dependent Density Functional Assessment of Plasmonic Behavior

The surface plasmon resonance has been theoretically investigated in gold nanowires by means of time-dependent density functional theory. Linear chains of Au atoms and nanowires with the structure of the fcc bulk gold grown along the < 110 > and < 111 > directions have been considered. The effects of changing the length and the section on the plasmon have been studied. Strong photoabsorption is found when the length is above 2 nm: in that case the absorption profile is characterized by a sharp peak, and its analysis reveals that many configurations contribute to the transition, confirming its collective nature as an s <- s intraband transition. As expected, the effect of increasing the length is reflected in a red shift of the plasmon.