Dynamics of He-4 droplets

Optimized variational calculations have been carried out for clusters of He -4 between N=20 and N=1000 atoms. For small cluster sizes with less or equa l to 112 particles, where comparisons with existing diffusion Monte Carlo r esults are possible, we find good agreement for the ground state energies a nd densities. Using a somewhat simpler approximation, we also calculate the bound state energies of He-3 atoms attached to these clusters. We then cal culate excitations and the dynamic structure function. The complex and nonl ocal self-energy introduced for that purpose gives access to the calculatio n of both elastic and inelastic scattering processes for He-4 and He-3 atom s impinging on the clusters. (C) 2001 American Institute of Physics.