Phase diagram of 4He adsorbed on graphite

We present results of a theoretical study of He-4 films adsorbed on graphite based on the continuous space worm algorithm. In the first layer, we find a domain-wall phase and a (7/16) registered structure between the commensurate (1/3) and the incommensurate solid phases. For the second layer, we find only superfluid and incommensurate solid phases. The commensurate phase found in a previous simulation work is only observed if first-layer particles are kept fixed; it disappears upon explicitly including their zero-point fluctuations. No evidence of any supersolid phase is found.