Ab Initio Calculation of Lattice Thermal Conductivity

An ab-initio-based theoretical approach was presented to accurately describe phonon thermal transport.Harmonic and anharmonic interatomic force constants (IFCs) are the only inputs required for exact solution of phonon Boltzmann equation, thus the crucial elements required to calculate thermal conductivity.In this work, first principles using density functional perturbation theory was employed to calculate the harmonic IFCs.The third order anharmonic IFCs are determined by 2n+1 theorem.The calculated lattice thermal conductivities for Si and Ge, both isotopically enriched and naturally occurring, are in excellent agreement with experimental data. MethodologyThis session illustrated the ab initio approach to calculate the harmonic and third-order anharmonic IFCs in the framework of density-functional perturbation theory (DFPT), and calculating thermal conductivity through the Boltzmann transport theory. A. Interatomic Force ConstantThe reciprocal-space harmonic IFCs is a combination of electronic and ionic parts，can be written as