Colloidal systems (and protein solutions) are often characterized by
attractive interactions whose range is much smaller than the particle size.
When this is the case and the interaction is spherical, systems obey a
generalized law of correspondent states (GLCS), first proposed by Noro and
Frenkel [ J.Chem.Phys. 113, 2941 (2000) ]. The thermodynamic properties become
insensitive to the details of the potential, depending only on the value of the
second virial coefficient B_2 and the density ρ. The GLCS does not
generically hold for the case of non-spherical potentials. In this Letter we
suggest that when particles interact via short-ranged small-angular amplitude
patchy interactions (so that the condition of only one bond per patch is
fulfilled) it is still possible to generalize the GLCS close to the liquid-gas
critical point. Keywords: Colloids, Second Virial Coefficient, Proteins
interactions, Short-ranged attractive attractions.Comment: 11 pages, 3 figures. Accepted for publication on J. Phys. Chem.