  We propose a computationally-efficient approach to multiscale simulation of
polycrystalline materials, based on the phase field crystal (PFC) model. The
order parameter describing the density profile at the nanoscale is
reconstructed from its slowly-varying amplitude and phase, which satisfy
rotationally-covariant equations derivable from the renormalization group. We
validate the approach using the example of two-dimensional grain nucleation and
growth.
