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SYCF: Symposium Cluster und Fullerene
SYCF 1: Homogene und heterogene Helium-Cluster
SYCF 1.5: Talk
Monday, March 15, 1999, 15:15–15:30, MP1
Alkali-Hen: An Example of Marginal Binding — •Marius Lewerenz — Zentralinstitut für Angewandte Mathematik, Forschungszentrum Jülich, D-52425 Jülich
The properties of alkali atoms attached to the surface of bulk helium and large clusters have been studied recently with several techniques. All evidence points towards weak binding to the surface of helium consistent with the alkali-helium well depth being even smaller than the He-He interaction.
As a first step towards the calculation of electronic spectra of alkali atoms attached to helium clusters we have studied the ground state structures and binding energies of mixed clusters of the type NaHen, LiHen, n=1… 100 with the diffusion quantum Monte Carlo method. The alkali atoms are found to give rise to slight distortions of the surfaces of large clusters and to reach binding energies of a few cm−1.
Reducing the number of helium atoms leads to extremely weakly bound small clusters which rival small pure helium clusters in their diffuse quantum nature. Contrary to widespread belief even the diatomic systems are found to support a single very long range bound state with J=0 comparable to the situation in He2.