The Impact Of Dissipation On Plasmonic Versus Non-Collective Excitation

We explore the impact of dissipation on the response of clusters and molecules to a laser field whereby dissipation is treated at the level of a quantum Relaxation Time Approach (RTA). Test cases are the metal cluster Na-40 with pronounced plasmon response and, for comparison, the H2O molecule with strong spectral fragmentation. Laser parameters are selected according to the spectral properties of the considered systems. We consider both on and off resonance laser irradiation and compare dynamical response in terms of net ionization, absorbed energy, and dipole response. The impact of dissipation is tested by comparison of results from RTA with mere mean-field dynamics at the level of time-dependent density functional theory. Only little differences between dissipative and mean-field dynamics are observed for off resonance irradiations. The situation is totally different for laser frequencies matching a resonance where we observe qualitative differences between the RTA and mean-field evolutions. Published by AIP Publishing.