  Tetrahedrite (copper antimony sulfosalt) is promising p-type themoeletric
material due to very low intrinsic thermal conductivity and moderately-high
power factor, with one of the limitations being lack of n-type variant to
create thermoelectric generator. In this paper, DFT calculations have been
carried out to study tetrahedrite doped with Li into structural voids,
LixCu12Sb4S13 (0 <= x <= 3). Enthalpies of formation shows that introduction of
Li into both 6b and 24g sites is energetically favorable. Dopants in those
positions differently affect rattling Cu(12e) behaviour, as well as vary in
magnitude of induced local disorder. Topological analysis of charge density
classifies tetrahedrite as closed-shell, ionic system of interactions with some
degree of covalency. Addition of Li increases bond strain and decreases
structure stability. Electronic band structure shows that for x>2.0, material
becomes n-type, however results are not precisely conclusive on whether
structure will be synthesizable, which should be determined experimentally.
