We present a first-principles theoretical approach to calculate the lattice thermal conductivity of diamond based on an exact solution of the Boltzmann transport equation. Density-functional perturbation theory is employed to generate the harmonic and third-order anharmonic interatomic force constants that are required as input. A central feature of this approach is that it provides accurate representations of the interatomic forces and at the same time introduced no adjustable parameters. The calculated lattice thermal conductivities for isotopically enriched and naturally occurring diamond are both in very good agreement with experimental data. The role of the scattering of heat-carrying acoustic phonons by optic branch phonons is also investigated. We show that inclusion of this scattering channel is indispensable in properly describing the thermal conductivity of semiconductors and insulators. The accurate adjustable-parameter-free results obtained herein highlight the promise of this approach in providing predictive descriptions of the lattice thermal conductivity of materials.

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We present calculations of the lattice thermal conductivity of silicon that incorporate several commonly used empirical models of the interatomic potential. Second-and third-order force constants obtained from these potentials are used as inputs to an exact iterative solution of the inelastic phonon Boltzmann equation, which includes the anharmonic three-phonon scattering as well as isotopic defect and boundary scattering. Comparison of the calculated lattice thermal conductivity with the experiment shows that none of these potentials provides satisfactory agreement. Calculations of the mode Grüneisen parameters and the linear thermal expansion coefficient help elucidate the reasons for this. We also examine a set of parameters for one of these empirical potentials that produces improved agreement with both the measured lattice thermal conductivity and the thermal expansion data.

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A five-year study reveals that the highly successful Toyota Motor Corporation seems to follow a different paradigm of design than other US and Japanese auto companies. This paper outlines 11 principles that appear to form the foundation of Toyota’s use of “Set-Based Concurrent Engineering.” Discussion of the principles includes illustrations from Toyota.