A molecular dynamics description of clusters in strong laser fields

Abstract.

We discuss from a theoretical perspective the energetic dynamics of clusters after irradiation with intense laser pulses in the regime of intensities larger than 10¹⁶ W/cm². To that end, we have developed a molecular dynamics (MD) model. The valence as well as the core electrons of each atom are treated as classical Coulomb interacting particles. A minimum of quantum information is embodied by associating a finite width to each electron which is adjusted to the energies and radii of the related atomic shells, thus being different for valence and core electrons. The model aims at high excitation but delivers satisfying physical properties for the initial phase of the process, i.e. it provides a stable cluster ground state and a reasonable description of optical response. We find that the pattern of electron emission versus laser intensity are well reproduced in comparison with fully quantum mechanical calculations. Finally, we produce first applications of the model to violent processes after strong laser irradiation for various medium large Na, Ar and Xe clusters.