Isotope effect on the quantum thermal transport of carbyne

Abstract

The isotope effect on the quantum thermal transport of carbyne is studied by combining the central insertion scheme and the non-equilibrium Green's function method based on density function theory. This combined method avoids the disadvantage of the cascading scattering model and scaling theory method, which in principle only can process the phonon with low-concentration (≤10%) isotope impurity scattering. Also, the molecular dynamics method greatly overestimates the carbyne thermal transport property. By using our combined method, the calculated thermal conductivity of 100% 12C carbyne with the phonon mean free path of 775 nm at room temperature is 4.44 × 103 W m−1 K−1. When a 12C carbyne consisting of 400 carbon atoms is randomly mixed with 13C or 14C atoms at 300 K, the largest isotope effect of thermal conductance locates at the mixing ratio of 50% 13C/14C. Compared to the pure 12C carbyne, the average thermal conductance is reduced by 30% and 49% for the 13C and 14C, respectively.