FourPhonon: An extension module to ShengBTE for computing four-phonon scattering rates and thermal conductivity

Quantum mechanical prediction of four-phonon scattering rates and reduced thermal conductivity of solids

Recently, first principle-based predictions of lattice thermal conductivity κ from perturbation theory have achieved significant success. However, it only includes three-phonon scattering due to the assumption that fourphonon and higher-order processes are generally unimportant. Also, directly evaluating the scattering rates of fourphonon and higher-order processes has been a long-standing chal...

Thermal conductivity spectroscopy technique to measure phonon mean free paths.

Size effects in heat conduction, which occur when phonon mean free paths (MFPs) are comparable to characteristic lengths, are being extensively explored in many nanoscale systems for energy applications. Knowledge of MFPs is essential to understanding size effects, yet MFPs are largely unknown for most materials. Here, we introduce the first experimental technique which can measure MFP distribu...

Phonon Scattering and Velocity Considerations in the Minimum Phonon Thermal Conductivity of Layered Solids above the Plateau

Impact of phonon-surface roughness scattering on thermal conductivity of thin si nanowires.

We present a novel approach for computing the surface roughness-limited thermal conductivity of silicon nanowires with diameter D<100 nm. A frequency-dependent phonon scattering rate is computed from perturbation theory and related to a description of the surface through the root-mean-square roughness height Delta and autocovariance length L. Using a full phonon dispersion relation, we find a q...

Phonon Transport and Thermal Conductivity Percolation in Random Nanoparticle Composites

In this paper, we investigated the effective thermal conductivity of three dimensional nanocomposites composed of randomly distributed binary nanoparticles with large differences (contrast ratio) in their intrinsic (bulk) thermal conductivity. When random composites are made from particles with very different thermal conductivity (large contrast ratio), a continuous phase of high thermal conduc...