  Coupled atomistic-continuum methods can describe large domains and model
dynamic material behavior for a much lower computational cost than traditional
atomistic techniques. However, these multiscale frameworks suffer from wave
reflections at the atomistic-continuum interfaces due to the numerical
discrepancy between the fine-scaled and coarse-scaled models. Such reflections
are non-physical and may lead to unfavorable outcomes such as artificial
heating in the atomistic region. In this work, we develop a technique to allow
the full spectrum of phonons to be incorporated into the coarse-scaled regions
of a periodic concurrent atomistic-continuum (CAC) framework. This scheme
tracks phonons generated at various time steps and thus allows multiple
high-frequency wave packets to travel between the atomistic and continuum
regions. Simulations performed with this method demonstrate the ability of the
technique to preserve the coherency of waves with a range of wavevectors as
they propagate through the domain. This work has applications for systems with
defined boundary conditions and may be extended to more complex problems
involving waves randomly nucleated from an impact within a multiscale
framework.
