2003/06/30 by Martin Hohenadler, Markus Aichhorn, Wolfgang von der Linden · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.68.184304
published as PRB 68, 184304 (2003) · 10 pages, 7 figures, REVTEX 4
arxiv created 2003/06/30 · arxiv updated 2009/11/30
Cluster perturbation theory in combination with the Lanczos method is used to compute the one-electron spectral function of the Holstein polaron in one and two dimensions. It is shown that the method allows reliable calculations using relatively small clusters, and at the same time significantly reduces finite-size effects. Results are compared with exact data and the relation to existing work is discussed. We also use a strong-coupling perturbation theory--equivalent to the Hubbard I approximation--to calculate the spectral function of the quarter-filled Holstein model of spinless fermions, starting from the exact atomic-limit Green function. The results agree well with previous calculations within the many-body coherent potential approximation.