  Colloidal systems present exciting opportunities to study clusters. Unlike
atomic clusters, which are frequently produced at extremely low density,
colloidal clusters may interact with one another. Here we consider the effect
of such interactions on the intra-cluster structure in simulations of colloidal
cluster fluids. A sufficient increase in density leads to a higher population
of clusters in the ground state. In other words, inter-cluster interactions
perturb the intra-cluster behaviour, such that each cluster may no longer be
considered as an isolated system. Conversely, for dilute, weakly interacting
cluster fluids little dependence on colloid concentration is observed, and we
thus argue that it is reasonable to treat each cluster as an isolated system.
