Coupled plasmon and phonon dynamics in embedded Na clusters

We investigate, from a theoretical perspective, the coupled electronic and ionic/atomic dynamics of Na clusters embedded in Ar matrices. The system is described by time-dependent density-functional theory for cluster electrons and classical motion for Na⁺ ions as well as for Ar atoms. The interaction with the surrounding Ar atoms is modelled by polarization potentials plus core repulsion. We use this model to study coupled electronic and ionic/atomic motion in embedded clusters following a very short laser pulse. For excitations in the non-linear regime, we find clear signs for the coherent coupling of the Mie plasmon resonance with ionic vibrations (phonons). In addition, an incoherent line stretching is observed which can be traced back to the turning point of ionic vibrations. The coupling to the atomic motion of the surroundings leads to a slow and far reaching rearrangement of the matrix. PACS 36.40.Gk; 36.40.Vz; 31.15.EW