The prospects of application of a mechanical model in describing the properties of planar and curved interfaces at low temperatures are investigated. It is shown that, in the framework of such approach, the Tolman length determining the first-order curvature correction to the surface tension, gamma, is equal to zero. In the range of small values of the radius of curvature, R, the mechanical approach overestimates considerably the value of gamma. For the Lennard-Jones potential the non-analyticity in the dependence gamma(1/R) is found at 1/R = 0. It disappears for potentials decreasing more rapidly with the distance between the particles. (C) 2004 Elsevier B.V. All rights reserved.