We present numerical studies of first-order and continuous filling transitions in wedges of arbitrary opening angle ψ, using a microscopic fundamental measure density functional model with short-ranged fluid-fluid forces and long-ranged wall-fluid forces. In this system the wetting transition characteristic of the planar wall-fluid interface is always first order regardless of the strength of the wall-fluid potential ɛ(w). In the wedge geometry, however, the order of the filling transition depends not only on ɛ(w) but also on the opening angle ψ. In particular we show that even if the wetting transition is strongly first order the filling transition is continuous for sufficient acute wedges. We show further that the change in the order of the transition occurs via a tricritical point as opposed to a critical end point. These results extend previous effective Hamiltonian predictions which were limited only to shallow wedges.

Department of Mathematics Imperial College London London SW7 2BZ United Kingdom

Department of Physical Chemistry Institute of Chemical Technology Prague 166 28 Praha 6 Czech Republic and Laboratory of Aerosols Chemistry and Physics Institute of Chemical Process Fundamentals Academy of Sciences 16502 Prague 6 Czech Republic

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