  A new numerical method is proposed for determining the low-frequency dynamics
of the charge carrier coupled to the deformable quantum lattice. As an example,
the polaron band structure is calculated for the one-dimensional Holstein
model. The adiabatic limit on the lattice, which cannot be reached by other
approaches, is investigated. In particular, an accurate description is obtained
of the crossover between quantum small adiabatic polarons, pinned by the
lattice, and large adiabatic polarons, moving along the continuum as classical
particles. It is shown how the adiabatic contributions to the polaron
dispersion, involving spatial correlations over multiple lattice sites, can be
treated easily in terms of coherent states.
