Dynamics of some constrained lattices
  We consider the dynamics of lattices which have constrained constitutive units flexible in only their mutual orientations.   A continuum description is derived through which it is shown that the models have zero shear velocity, free-particle like internal rotational modes and volume decreasing linearly with temperature. The relevance of modelsto a range of problems is pointed out. 
M. E. Simon and C. M. Varma (Lucent Technologies)