2008/10/08 by Glen L. Goodvin, Mona Berciu
Materials Science · Physics and Astronomy · #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.235120
published as Phys. Rev. B 78, 235120 (2008) · 15 pages, 10 figures
arxiv created 2008/10/08 · openalex publication_date 2008/12/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We generalize the momentum average (MA) approximation to study the properties of models with gq momentum-dependent electron-phonon coupling. As in the case of the application of the original MA to the Holstein model, the results are analytical, numerically trivial to evaluate, exact for both zero bandwidth and for zero electron-phonon coupling, and accurate everywhere in parameter space. Comparison with available numerical data confirms this accuracy. We then show that further improvements can be obtained based on variational considerations using the one-dimensional breathing-mode Hamiltonian as a specific example. For example, by using this variational MA, we obtain ground-state energies within at most 0.3% error of the numerical data.