  We study the interfacial thermal conductance of grain boundaries (GBs)
between monolayer graphene and hexagonal boron nitride (h-BN) sheets using a
combined atomistic approach. First, realistic samples containing graphene/h-BN
GBs with different tilt angles are generated using the phase-field crystal
(PFC) model developed recently [P. Hirvonen \textit{et al.}, Phys. Rev. B
\textbf{100}, 165412 (2019)] that captures slow diffusive relaxation
inaccessible to molecular dynamics (MD) simulations. Then, large-scale MD
simulations using the efficient GPUMD package are performed to assess heat
transport and rectification properties across the GBs. We find that lattice
mismatch between the graphene and h-BN sheets plays a less important role in
determining the interfacial thermal conductance as compared to the tilt angle.
In addition, we find no significant thermal rectification effects for these
GBs.
