Effective modelling of the Seebeck coefficient of Fe₂VAl

Previous first-principles calculations have failed to reproduce many of the key thermoelectric features of Fe₂VAl, e.g. the maximum values of the Seebeck coefficient S and its asymmetry with respect to the chemical potential. Also, previous theoretical predictions suggested that the pseudo band gap of Fe₂VAl switches from indirect to direct upon doping. In this work, we report first-principles calculations that correctly reproduce the experimentally measured thermoelectric properties of Fe₂VAl. This is achieved by adding a larger Hubbard U term to V atoms than to Fe atoms and including a scissors operator afterwards. As a result, bulk Fe₂VAl is modelled as a gapless semiconductor with maximum S values of 76 and  -158 [Formula: see text]V K^-1 for p - and n-type, respectively, which agree well with the experimental measurements.