Revisiting thermal transport in single-layer graphene: On the applicability of thermal snapshot interatomic force constant extraction methodology for layered materials

S Alam and AG Gokhale and A Jain, JOURNAL OF APPLIED PHYSICS, 133, 215102 (2023).

DOI: 10.1063/5.0152112

The thermal conductivities of single-/bi-layer graphene and bulk- graphite are obtained using the Boltzmann transport equation (BTE) framework by accounting for three-phonon and four-phonon scatterings. For single-layer graphene, the thermal conductivity and interatomic force constants obtained using temperature-independent finite- difference, and temperature-dependent molecular dynamics-based approaches agree with each other. The use of the thermal snapshot approach to get temperature-dependent force constants results in a non- physical description of interatomic distances for single-layer graphene. The predicted thermal conductivity at room temperature using finite- difference based force constants is 800 W/m K, which is a severe under- prediction of experimentally measured values. For bi-layer graphene and bulk graphite, the thermal snapshot methodology is applicable and thermal conductivity changes by 25% and 5% with temperature-dependent force constants. The effect of four-phonon scattering is less than 10% on the predicted thermal conductivity of bi-layer graphene and graphite, and the obtained thermal conductivities using thermal snapshot methodology are in agreement with the literature. The limitation in the prediction of thermal conductivity of single-layer graphene via the BTE approach stems from non-accountability of temperature-dependence in finite-difference based force constants and non-physical description of interatomic bonds in thermal snapshot based force constants extraction for planar 2-atoms unitcell of single layer graphene.

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