The dynamical response of metallic clusters up to 10 3 atoms is investigated using the restricted molecular dynamics simulations scheme. Exemplarily, sodium like material is considered. Correlation functions are evaluated to investigate the spatial structure of collective electron excitations and optical response of laser excited clusters. In particular, the spectrum of bi-local correlation functions shows resonances representing different modes of collective excitations inside the nano plasma. The spatial structure, the resonance energy and width of the eigenmodes have been investigated for various values of electron density, temperature, cluster size and ionization degree. Comparison with bulk properties is performed and the dispersion relation of collective excitations is discussed.

The time evolution of laser excited small clusters such as Na309 is investigated using a classical MD simulation code. Results for the electron phase space distribution are analyzed. We are interested in time dependent density and temperature profiles. The question of local thermal equilibrium is addressed comparing the simulated profiles with predictions from equilibrium statistical physics. Once the local thermal equilibrium is established, the time evolution of collective modes of the excited electron system can be investigated. For this, a restricted MD simulation scheme has been developed.

The dielectric function of dense plasmas is treated within a many-particle linear response theory beyond the RPA. In the long-wavelength limit, the dynamical collision frequency can be introduced which is expressed in terms of momentum and force auto-correlation functions (ACF). Analytical expressions for the collision frequency are considered for bulk plasmas, and reasonable agreement with MD simulations is found. Different applications such as Thomson scattering, reflectivity, electric and magnetic transport properties are discussed. In particular, experimental results for the static conductivity of inert gas plasmas are now well described.The transition from bulk properties to finite cluster properties is of particular interest. Within semiclassical MD simulations, single-time characteristics as well as two-time correlation functions are evaluated and analyzed. In particular, the Laplace transform of current and force ACFs show typical structures which are interpreted as collective modes of the microplasma. The damping rates of these modes are size dependent. They increase for the transition from small clusters to bulk plasmas.

The charge of ionized metal clusters is investigated at high temperatures. Molecular Dynamics (MD) simulations are applied to describe the particle motion. While the electrons are treated as separate particles, the interaction with the ion cores is described as an external jellium potential. The final cluster charge is determined by classifying the particles into free and bound electrons. A relation between the cluster charge and cluster sizes as well as temperatures is derived from MD simulations and simple kinetic model calculations. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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