Structural, elastic, electronic, optical and thermal properties of c-SiGe2N4 A. Bouhemadou, Y. Al-Douri, R. Khenata and K. Haddadi Eur. Phys. J. B, 71 2 (2009) 185-194 Published online: 18 August 2009 DOI: 10.1140/epjb/e2009-00272-6