FINITE-SIZE SCALING FOR CRITICAL FILMS

The universal scaling function of the finite-size contribution to the free energy of O.(N) symmetric systems confined between two parallel plates at distance L is calculated by field-theoretical methods close to T(c,bulk) and for five different boundary conditions. The asymptotic behavior for large L of the specific heat at T(c,b) is computed explicitly, thus allowing quantitative experimental tests. We discuss the implications of our results for surface forces and wetting films. Universal amplitudes for the surface free energy are also presented.