Impact of nuclear vibrations on van der Waals interactions and radiative heat transfer in graphene

We apply a recent theoretical framework describing thermal and quantum electromagnetic phenomena arising from the coupling of photons and phonons in molecular systems, including van der Waals interactions and radiative heat transfer, to interactions among parallel sheets of neutral graphene and metallic substrates. In particular, we show that atom-scale features as well as contributions of phonons to the response of graphene, as captured in ab-initio density functional theory calculations, along with long-range retarded electromagnetic fields, are of utmost importance to describing its van der Waals interactions and radiative heat transfer over a broad range of length scales; interactions no longer behave as simple power laws in terms of surface separation and show noticeable temperature sensitivity at separations well below the micron-scale radiative thermal wavelength. The contributions of phonons and atom-scale effects to the response are largely neglected in continuum treatments of the electromagnetic response of neutral graphene, which typically consider only the electronic contributions to the response derived from a tight-binding model; consequently, we observe significant differences in the predictions of our microscopic framework from such macroscopic treatments.