Two-dimensional clusters of liquid 4 He

The binding energies of two-dimensional clusters (puddles) of 4 He are calculated in the framework of the diffusion Monte Carlo method. The results are well fitted by a mass formula in powers of x=N - 1 / 2 , where N is the number of particles. The analysis of the mass formula allows for the extraction of the line tension, which turns out to be 0.121 K/A. Sizes and density profiles of the puddles are also reported.