  Colloidal particles can spontaneously self-assemble into ordered structures,
which not only can manipulate the propagation of light, but also vibration or
phonons. Using Monte Carlo simulation, we study the self-assembly of perfectly
aligned segment rod particles with lateral flat cutting. Under the help of
surface attractions, we find that particles with different cutting degree can
self-assemble into different crystal phases characterized by bond coordination
z that varies from 3 to 6. Importantly, we identify a transformable
super-isostatic structures with pgg symmetry and redundant bonds (z=5). We find
that this structure can support either the soft bulk model or soft edge model
depending on its Poisson's ratio which can be tuned from positive to negative
by a uniform soft deformation. Importantly, the bulk soft modes are associated
with states of self-stress along the direction of zero strain during the
uniform soft deformation. This self-assembled transformable super-isostatic
structure may act as mechanical metamaterials with potential application in
micro-mechanical engineering.
