"Pseudoisomorphs" in liquids with intramolecular degrees of freedom
  Computer simulations show that liquids of molecules with harmonic intramolecular bonds may have "pseudoisomorphic" lines of approximately invariant dynamics in the thermodynamic phase diagram. We demonstrate that these lines can be identified by requiring scale invariance of the inherent-structure reduced-unit low-frequency vibrational spectrum evaluated for a single equilibrium configuration. This rationalizes why excess-entropy scaling, density scaling, and isochronal superposition apply for many liquids with internal degrees of freedom. 
Andreas Elmerdahl Olsen, Jeppe C. Dyre, and Thomas B. Schr{\o}der
cond-mat.soft cond-mat.other cond-mat.stat-mech