Structural, stability and thermoelectric properties for the monoclinic phase of NaSbS2 and NaSbSe2: A theoretical investigationMahmoud M.A. Mahmoud, Daniel P. Joubert and Mahlaga P. MolepoEur. Phys. J. B, 92 9 (2019) 214DOI: https://doi.org/10.1140/epjb/e2019-90712-y