Cove-edge-induced vibrational confinement and weakened collective phonon transport in graphene nanoribbons

Periodic cove edges alter heat conduction in graphene nanoribbons in ways that are not fully captured by geometric boundary scattering. We investigate this effect using a graphene-nanoribbon-specific neuroevolution potential together with molecular dynamics, phonon Monte Carlo simulations, lattice dynamics, and full linearized phonon Boltzmann transport calculations. Cove-edged graphene nanoribbons exhibit lower thermal conductivity than pristine armchair nanoribbons over the length and width ranges considered. The conductivity reduction obtained from molecular dynamics is larger than that predicted by the semiclassical Monte Carlo model. The residual fraction is greatest at short lengths and small widths, whereas the Monte Carlo boundary contribution becomes relatively more important as either dimension increases. Participation ratios and real-space eigenvectors identify partially confined and strongly edge-confined modes in the low- and intermediate-frequency ranges, showing how the cove geometry reconstructs the vibrational eigenstates beyond a purely geometric boundary-scattering picture. The cove-edged ribbons also show a smaller collective correction beyond the relaxation-time approximation and a lower transport-weighted Normal-to-Umklapp scattering-rate ratio. These results indicate that cove-edge patterning changes both the vibrational eigenstates and the intrinsic scattering balance, thereby reducing the mode-coupling correction beyond the independent-mode approximation.