Applying a continuous-time quantum Monte-Carlo algorithm we calculate the exact coherent band dispersion and the density of states of a two dimensional lattice polaron in the region of parameters where any approximation might fail. We find an isotope effect on the band structure, which is different for different wave-vectors of the Brillouin zone and depends on the radius and strength of the electron-phonon interaction. An isotope effect on the electron spectral function is also discussed.
This is a pre-print. It is also available at: http://arxiv.org/abs/cond-mat/0407217. The definitive version, KORNILOVITVH, V.V. and ALEXANDROV, A.S., 2005. Isotope effect on the electron band structure of doped insulators. Physics Review B, 70, 224511, is available at: http://prb.aps.org/