Calculation of thermomagnetic properties using first-principles density functional theory

The BoltzWann code uses the first-principles density-functional theory to calculate the material’s response to an electric field and temperature gradient within the constant relaxation time approximation. We extend this code to include the response of the system to a magnetic field. The carrier dynamic is described by the semi-classical Boltzmann transport equation. This equation is solved in the presence of an external magnetic field within the constant relaxation time approximation and using the Jones–Zener expansion. This is done through a Wannier interpolation of the density functional theory bands using the Boltzwann code, followed by the computation of group velocities and effective masses leading to the energy-dependent transport function. This work leads to a generalized method for the calculation of thermomagnetic properties of materials. The results are validated by comparison to the analytical solutions of the thermomagnetic properties for several simple energy dispersion types and close agreements at moderate computational costs are achieved. This method can pave the path for the discovery of materials with potentially high thermomagnetic power factor.