| We have studied thin films in the 3D Ising and XY universality classes. We consider periodic, free and symmetry breaking boundary conditions. We have simulated the improved Blume-Capel model in the Ising universality class and the improved 2-component φ4 model in the XY universality class. An important issue in analyzing Monte Carlo and experimental data for films are corrections to scaling. Since we simulate an improved model, leading corrections to scaling, which are proportional to L0-ω, where L0 is the thickness of the film and ω ≈ 0.8, can be ignored. This allows us to focus on corrections to scaling that are caused by the boundary conditions. We confirm the theoretical expectation that these corrections can be accounted for by an effective thickness L0,eff = L0 + Ls. We compare our results for the scaling functions θ of the thermal Casimir force with previous Monte Carlo simulations, field theoretic results, the local-functional method and experiments. |
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