Abstract
A series of weak-coupling perturbation theories that include the lowest-order vertex corrections are applied to the attractive Holstein model in infinite dimensions. The approximations are chosen to reproduce the iterated perturbation theory in the limit of half-filling and large phonon frequency (where the Holstein model maps onto the Hubbard model). Comparison is made with quantum Monte Carlo solutions to test the accuracy of different approximation schemes.
- Received 23 June 1998
DOI:https://doi.org/10.1103/PhysRevB.58.11613
©1998 American Physical Society