International audienceWe investigate Na clusters embedded in Ar matrices. The surrounding Ar atoms are modeled in terms of their dynamical polarizability and the strong electron repulsion. The calibration of the model is discussed. First results for the non-linear optical response of the Na clusters are presented for the test case of Na8 embedded in Ar ensembles of different sizes. It is shown that blue shift through core repulsion and red shift through dipole polarizability counterweight each other to the end that very little global shift is seen in the spectra. This feature persists to all excitation strengths considered. There are, however, detailed effects, such as for example the Landau fragmentation of the Mie plasmon peak

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Abstract. Using a combined quantum mechanical/classical method, we study the dynamics of deposition of small Na clusters on Ar(001) surface. We work out basic mechanisms by systematic variation of substrate activity, impact energy, cluster orientations, cluster sizes, and charges. The soft Ar material is found to serve as an extremely efficient shock absorber which provides cluster capture in a broad range of impact energies. Reflection is only observed in combination with destruction of the substrate. The kinetic energy of the impinging cluster is rapidly transfered at first impact. The distribution of the collision energy over the substrate proceeds very fast with velocity of sound. The full thermalization of ionic and atomic energies goes at a much slower pace with times of several ps. Charged clusters are found to have a much stronger interface interaction and thus get in significantly closer contact with the surface.

We present a microscopic model for Na clusters embedded in raregas matrices. The valence electrons of the Na cluster are described by time-dependent density-functional theory at the level of the local-density approximation (LDA). Particular attention is paid to the semi-classical picture in terms of Vlasov-LDA. The Na ions and Argon atoms are handled as classical particles whereby the Ar atoms carry two degrees of freedom, position and dipole polarization. The interaction between Na ions and electrons is mediated through local pseudo-potentials. The coupling to the Ar atoms is described by (long-range) polarization potentials and (short-range) repulsive cores. The ingredients are taken from elsewhere developed standards. A final fine-tuning is performed using the NaAr molecule as benchmark. The model is then applied to embedded systems Na8ArN. By close comparison with quantum-mechanical results, we explore the capability of the Vlasov-LDA to describe such embedded clusters. We show that one can obtain a reasonable description by appropriate adjustments in the fine-tuning phase of the model.Comment: 17 pages, 7 figures, submitted to Annalen der Physi