A size-consistent Gruneisen-quasiharmonic approach for lattice thermal conductivity

We propose a size-consistent Graneisen-quasiharmonic approach (GQA) to calculate the lattice thermal conductivity kappa(l) where the Graneisen parameters that measure the degree of phonon anharmonicity are calculated directly using first-principles calculations. This is achieved by identifying and modifying two existing equations related to the Slack formulae for kappa(l) that suffer from the size-inconsistency problem when dealing with non-monoatomic primitive cells (where the number of atoms in the primitive cell n is greater than one). In conjunction with other thermal parameters such as the acoustic Debye temperature theta(a) that can also be obtained within the GQA, we predict kappa(l) for a range of materials taken from the diamond, zincblende, rocksalt, and wurtzite compounds. The results are compared with that from the experiment and the quasiharmonic Debye model (QDM). We find that in general the prediction of theta(a) is rather consistent among the GQA, experiment, and QDM. However, while the QDM somewhat overestimates the Graneisen parameters and hence underestimates kappa(l) for most materials, the GQA predicts the experimental trends of Graneisen parameters and kappa(l) more closely. We expect the GQA with the modified Slack formulae could be used as an effective and practical predictor for kappa(l) , especially for crystals with large n. Copyright (C) 2022 EPLA