Abstract
We compute the Holstein polaron spectral function on a one-dimensional ring using the finite-temperature Lanczos method. With increasing additional features in the spectral function emerge even at temperatures below the phonon frequency. We observe a substantial spread of the spectral weight towards lower frequencies and the broadening of the quasiparticle (QP) peak. In the weak-coupling regime the QP peak merges with the continuum in the high- limit. In the strong-coupling regime the main features of the low- spectral function remain detectable up to the highest used in our calculations. The effective polaron mass shows a nonmonotonic behavior as a function of at small phonon frequency but increases with at larger frequencies. The self-energy remains independent even at elevated in the frequency range corresponding to the polaron band, while at higher frequencies it develops a distinguishable dependence. Analytical expressions for the first few frequency moments are derived, and they agree well with those extracted from numerical calculations in a wide- regime.
- Received 27 February 2019
- Revised 9 September 2019
DOI:https://doi.org/10.1103/PhysRevB.100.094307
©2019 American Physical Society