The anharmonic electron-phonon problem

TL;DR

This paper investigates the effects of anharmonicity on electron-phonon interactions using quantum Monte Carlo simulations in infinite dimensions, revealing persistent charge order and limited impact on superconducting transition temperatures.

Contribution

It provides a detailed analysis of anharmonic effects on electron-phonon systems, highlighting their influence on charge order and superconductivity without increasing transition temperatures.

Findings

Charge-density-wave order persists at half filling despite anharmonicity.

Superconductivity is enhanced away from half filling.

Anharmonicity does not increase maximum transition temperatures.

Abstract

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.