Optical phonon-driven modulation of interlayer thermal transport in stacked diamane

Abstract

In this work, we systematically investigate the cross-plane thermal conductivity in stacked diamane via molecular dynamics simulations, focusing on the effects of stacking orientation, external pressure, interlayer coupling strength, and twist angle. By combining spectral heat current decomposition and spectral energy density analysis, we identify high-frequency optical phonons within 10–15 THz as the dominant heat carriers across interfaces—a selectivity arising from interfacial hydrogen termination that strengthens the coupling of these modes. Their lifetimes and coupling strengths are highly sensitive to structural configuration and mechanical modulation. Our results reveal that parallel stacking, increased pressure, and stronger interlayer coupling significantly enhance thermal conductivity by stabilizing optical modes and suppressing phonon scattering. In contrast, increasing the twist angle introduces structural incommensurability, which reduces phonon lifetimes and leads to substantial suppression of thermal transport. These findings underscore the pivotal role of optical phonons in governing interfacial thermal transport as well as establish an optimal strategy for engineering thermal conductivity in 2D vdW materials.