The Asakura-Oosawa model for colloid-polymer mixtures is studied by MonteCarlo simulations at densities inside the two-phase coexistence region of fluidand solid. Choosing a geometry where the system is confined between two flatwalls, and a wall-colloid potential that leads to incomplete wetting of thecrystal at the wall, conditions can be created where a single nanoscopicwall-attached crystalline cluster coexists with fluid in the remainder of thesimulation box. Following related ideas that have been useful to studyheterogeneous nucleation of liquid droplets at the vapor-liquid coexistence, weestimate the contact angles from observations of the crystalline clusters inthermal equilibrium. We find fair agreement with a prediction based on Young'sequation, using estimates of interface and wall tension from the study of flatsurfaces. It is shown that the pressure versus density curve of the finitesystem exhibits a loop, but the pressure maximum signifies the "dropletevaporation-condensation" transition and thus has nothing in common with a vander Waals-like loop. Preparing systems where the packing fraction is deepinside the two-phase coexistence region, the system spontaneously forms a "slabstate", with two wall-attached crystalline domains separated by (flat)interfaces from liquid in full equilibrium with the crystal in between;analysis of such states allows a precise estimation of the bulk equilibriumproperties at phase coexistence.
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