The anharmonic electron-phonon problem
  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. 
J. K. Freericks (Georgetown), Mark Jarrell (Cincinnati), and G. D.   Mahan (Tennessee and ORNL)