Thermoelectric transport calculations using the Landauer approach, ballistic quantum transport simulations, and the Buttiker approximation

An implementation of the Landauer approach utilizing the ballistic quantum transport package Kwant to calculate thermoelectric transport properties is presented. Incoherent scattering is included by an approach suggested by Buttiker, where scattering is mimicked by virtual contacts (Buttiker probes). In this paper we present the implementation and provide a simple validation by comparing results to the Boltzmann transport equation (BTE) for bulk CdTe and a simple short period superlattice . The electronic structure, serving as a base for fitting a tight-binding model, is calculated from first-principles. From there, the electronic structure on a dense k-point grid is generated and passed to the BTE routines, while the transmission coefficients in the Landauer approach are calculated from Green’s functions based on the tight-binding model. Our results show good agreement between the results from the Buttiker and the BTE calculations, which indicates a successful initial implementation. We discover significant performance bottlenecks tied to the density of the Buttiker probes and as such the implementation needs additional optimization to be viable for production work.