Photoemission spectroscopy and sum rules in dilute electron-phonon systems
Hewlett-Packard Labs, MS 1L-1123 - 1501 Page Mill Road,
Palo Alto, CA, 94304, USA
Accepted: 31 May 2002
A family of exact sum rules for the one-polaron spectral function in the low-density limit is derived. An algorithm to calculate energy moments of arbitrary order of the spectral function is presented. Explicit expressions are given for the first two moments of a model with general electron-phonon interaction, and for the first four moments of the Holstein polaron. The sum rules are linked to experiments on momentum-resolved photoemission spectroscopy. The bare electronic dispersion and the electron-phonon coupling constant can be extracted from the first and second moments of the spectrum. The sum rules could serve as constraints in analytical and numerical studies of electron-phonon models.
PACS: 71.38.-k – Polarons and electron-phonon interactions / 79.60.-i – Photoemission and photoelectron spectra
© EDP Sciences, 2002