We provide the parameters of Stillinger-Weber potentials for GeSiSn ternary mixed systems. These parameters can be used in molecular dynamics (MD) simulations to reproduce phonon properties and thermal conductivities. The phonon dispersion relation is derived from the dynamical structure factor, which is calculated by the space-time Fourier transform of atomic trajectories in an MD simulation. The phonon properties and thermal conductivities of GeSiSn ternary crystals calculated using these parameters mostly reproduced both the findings of previous experiments and earlier calculations made using MD simulations. The atomic composition dependence of these properties in GeSiSn ternary crystals obtained by previous studies (both experimental and theoretical) and the calculated data were almost exactly reproduced by our proposed parameters. Moreover, the results of the MD simulation agree with the previous calculations made using a time-independent phonon Boltzmann transport equation with complicated scattering mechanisms. These scattering mechanisms are very important in complicated nanostructures, as they allow the heat-transfer properties to be more accurately calculated by MD simulations. This work enables us to predict the phonon-and heat-related properties of bulk group IV alloys, especially ternary alloys.

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This study examines whether mass or potential disorder is more effective at reducing the thermal conductivity and phonon properties in group IV alloys using molecular dynamics (MD) simulation. In this investigation, virtual atoms were used so that the atomic mass and the interatomic potential could be varied independently. The effects of potential disorder on the thermal conductivity and phonon properties are smaller than those associated with mass disorder. The suppression of thermal conductivity by alloying is attributed only to the effects of mass disorder. In the phonon lifetime calculation, the lifetime of the phonon determined by the scattering due to potential disorder is ten times longer than that due to mass disorder. This difference is so large that the contribution of potential disorder to phonon lifetime is effectively negligible. Thus, a binary interatomic potential is unnecessary to accurately estimate the thermal conductivity of the group IV alloys.