The electronic, optical, and thermodynamical properties of tetragonal, monoclinic, and orthorhombic M3N4 (M = Si, Ge, Sn): A first-principles study
Chen Dong1, †, Cheng Ke2, Qi Bei-Ying1
       

(color online) The same as Fig. 1, but for o-M3N4 (M=Si, Ge, Sn).