  By means of first principles schemes based on magnetically constrained
density functional theory and on the band unfolding technique we study the
effect of doping on the conducting behaviour of the Lifshitz magnetic insulator
NaOsO3. Electron doping is treated realistically within a supercell approach by
replacing sodium with magnesium at different concentrations. Our data indicate
that by increasing carrier concentration the system is subjected to two types
of transition: (i) insulator to bad metal at low doping and low temperature and
(ii) bad metal to metal at high doping and/or high-temperature. The predicted
doping-induced insulator to metal transition (MIT) has similar traits with the
temperature driven MIT reported in the undoped compound. Both develops in an
itinerant background and exhibit a coupled electronic and magnetic behaviour
characterized by the gradual quenching of the (pseudo)-gap associated with an
reduction of the local spin moment. Unlike the temperature-driven MIT, chemical
doping induces substantial modifications of the band structure and the MIT
cannot be fully described as a Lifshitz process.
