Postponing the dynamical transition density using competing interactions
Systems of dense spheres interacting through very short-ranged attraction are
known from theory, simulations and colloidal experiments to exhibit dynamical
reentrance. The liquid state can thus be fluidized to higher densities than
otherwise possible with interactions that are purely repulsive or long-ranged
attractive. A recent mean-field, infinite-dimensional calculation predicts that
the dynamical arrest of the fluid can be further delayed by adding a
longer-ranged repulsive contribution to the short-ranged attraction. We examine
this proposal by performing extensive numerical simulations in a
three-dimensional system. We first find the short-ranged attraction parameters
necessary to achieve the densest liquid state, and then explore the parameters
space for an additional longer-ranged repulsion that could enhance the effect.
In the family of systems studied, no significant (within numerical accuracy)
delay of the dynamical arrest is observed beyond what is already achieved by
the short-ranged attraction. Possible explanations are discussed.