  Many experimental systems exist that possess charge-density-wave order in
their ground state. While this order should be able to be described with models
similar to those used for superconductivity, nearly all systems have a ratio of
the charge-density-wave order parameter to the transition temperature that is
too high for conventional theories. Recent work explained how this can happen
in harmonic systems, but when the lattice distortion gets large, anharmonic
effects must play an increasingly important role. Here we study the gap ratio
for anharmonic charge-density wave systems to see whether the low-temperature
properties possess universality as was seen previously in the transition
temperature and to see whether the explanation for the large gap ratios
survives for anharmonic systems as well.
