title: Nonuniversal size dependence of the free energy of confined systems near criticality.
abstract: The singular part of the finite-size free-energy density f(s) of the O(n) symmetric phi(4) field theory is calculated for confined geometries of linear size L with periodic boundary conditions in the large-n limit and with Dirichlet boundary conditions in one-loop order. We find that both a sharp cutoff and a subleading long-range interaction cause a leading nonuniversal L dependence of f(s) near T(c). This implies a significant restriction for the validity of universal finite-size scaling for model systems and real systems. For film geometry we predict a leading nonuniversal contribution to the critical Casimir force above the superfluid transition of (4)He.
authors.affiliation: Institute of Theoretical Physics, Academia Sinica, P.O. Box 2735, Beijing 100080, China.
authors.forename: X S
authors.initials: XS
authors.lastname: Chen
authors.forename: V
authors.initials: V
authors.lastname: Dohm