  We use numerical simulations to study the phase behavior of a system of
purely repulsive soft dumbbells as a function of size ratio of the two
components and their relative degree of deformability. We find a plethora of
different phases which includes most of the mesophases observed in
self-assembly of block copolymers, but also crystalline structures formed by
asymmetric, hard binary mixtures. Our results detail the phenomenological
behavior of these systems when softness is introduced in terms of two different
classes of inter-particle interactions: (a) the elastic Hertz potential, that
has a finite energy cost for complete overlap of any two components, and (b) a
generic power-law repulsion with tunable exponent. We discuss how simple
geometric arguments can be used to account for the large structural variety
observed in these systems, and detail the similarities and differences in the
phase behavior for the two classes of potentials under consideration.
