Collapse of an adsorbate island on substrate pillars

We study an equilibrium shape of an adsorbate solid island on a substrate surface patterned with arrays of pillars. For a large island with a weak wettability to the substrate, an island sits on top surfaces of pillars, in a state called Cassie-Baxter CB state. In the opposite case of a small island with a strong wettability, the island collapses in the space between pillars, forming the so-called Wenzel W state. The collapse transition from CB to W state is studied in the phase space of the island volume and the wettability. Theory leads to collapse transition lines for an island with only 100 facets at zero temperature. They are in good agreement with the transitions observed in kinetic Monte Carlo simulations of an island with additional 110 and 111 facets at a finite temperature.