  Understanding phonon scattering by topological defects in graphene is of
particular interest for thermal management in graphene-based devices. We
present a study that quantifies the roles of the different mechanisms governing
defect phonon scattering by comparing the effects of ten different defect
structures using molecular dynamics. Our results show that phonon scattering is
mainly influenced by mass density difference, with general trends governed by
the defect formation energy and typical softening behaviors in the phonon
density of state. The phonon scattering cross-section is found to be far larger
than that geometrically occupied by the defects. We also show that the lattice
thermal conductivity can be reduced by a factor of up to ~30 in the presence of
the grain boundaries formed by these defects.
