  The anharmonic electron-phonon problem is solved in the infinite-dimensional
limit using quantum Monte Carlo simulation. Charge-density-wave order is seen
to remain at half filling even though the anharmonicity removes the
particle-hole symmetry (and hence the nesting instability) of the model.
Superconductivity is strongly favored away from half filling (relative to the
charge-density-wave order) but the anharmonicity does not enhance transition
temperatures over the maximal values found in the harmonic limit.
