  We consider rapid cooling processes in classical, 3-dimensional, purely
repulsive binary mixtures in which an initial infinite-temperature (ideal-gas)
configuration is instantly quenched to zero temperature. It is found that such
systems display two kinds of ordering processes, the type of which can be
controlled by tuning the interactions between unlike particles. While strong
inter-species repulsion leads to chemical ordering in terms of an unmixing
process, weak repulsion gives rise to spontaneous crystallization, maintaining
chemical homogeneity. This result indicates the existence of a transition in
the topography of the underlying potential-energy landscape as the
intra-species interaction strength is varied. Furthermore, the dual-type
behavior appears to be universal for repulsive pair-interaction
potential-energy functions in general, with the propensity for the
crystallization process being related to their behavior in the neighborhood of
zero separation.
