Structure and contact angle of liquid He-4 droplets on a Cs surface

By using a density-functional approach, we have studied the T=0 nonwetting behavior of liquid He-4 nanodroplets on a Cs surface. The minimum energy structure of the droplets is determined and its dependence upon size is investigated. The comparison with a simple model of droplet adsorption suggests a way to extrapolate our result to the experimentally accessible case of macroscopic droplets. In particular, a value for the contact angle of macroscopically thick droplets, which is an important parameter in wetting phenomena, is predicted. Our calculated value for the contact angle is in semiquantitative agreement with recent experimental observations.