We investigate the energetics and structure of ${}^3$He layers adsorbed on graphite in the submonolayer regime. We have assumed translational invariance parallel to the substrate, however, taking into account the perpendicular motion of the atoms. The energetics and stability properties can be interpreted in terms of a model that regards the film as a collection of two-dimensional (2D) systems in momentum space, whose parameters, however, arise from a full 3D self-consistent calculation. The range of validity of the model is established, indicating that, in addition to describing the submonolayer regime, it can be applied as well to films admitting several fluid layers such as those appearing on weakly binding substrates. We can also make a preliminary analysis of the ability of the 3D-energy functional to reproduce the equation of state of the film.

• Received 7 July 1997

DOI:https://doi.org/10.1103/PhysRevB.57.13258