Crossover behavior of the susceptibility and the specific heat near a second-order phase transition

Simple crossover equations for the susceptibility and the specific heat in zero field have been obtained on the basis of the renormalization-group method and ε-expansion. The equations contain the Ginzburg number as a parameter. At temperatures near the critical temperature, scaling behavior including the first Wegner corrections is reproduced. At temperatures far away from the critical temperature the classical Landau expansion with square-root corrections is recovered. For small values of the Ginzburg number the crossover equations approach a universal form. The equations are applied to represent experimental specific heat data for CH4, C2H6, Ar, O2 and CO2 along the critical isochore in a universal form.