  Using first-principles method and Boltzmann theory, we provide an accurate
prediction of the electronic band structure and thermoelectric transport
properties of alpha-MgAgSb. Our calculations demonstrate that only when an
appropriate exchange-correlation functional is chosen can we correctly
reproduce the semiconducting nature of this compound. By fine tuning the
carrier concentration, the thermoelectric performance of alpha-MgAgSb can be
significantly optimized, which exhibits a strong temperature dependence and
gives a maximum ZT value of 1.7 at 550 K.
