  We present a simulation study of colloidal particles having very short range
attractions. In particular, we investigate the interplay between the effective
attractive range and the viscoelastic properties of the gels that form when the
temperature of the system is sufficiently low. Using Brownian dynamics
simulations we study particles with different size and interaction range, and
characterize the mechanical properties of the gels by performing small
amplitude oscillatory and transient starts-up shear simulations. We found that
the effective attractive range is a key parameter affecting the gel
viscoelastic properties. The crossover frequency between the storage and loss
moduli and the time to reach the maximum stress in the start-up test are both
simple functions of the effective attractive range.
