Theoretical prediction of the structural and electronic properties of pseudocubic X3As4 (X=C, Si, Ge and Sn) compounds

The structural and electronic properties of X3As4 (X=C, Si, Ge and Sn) compounds were investigated using density functional theory (DFT) calculations. We employed both the generalized-gradient approximation (GGA), which is based on exchange-correlation energy optimization to calculate the total energy and the Engel-Vosko (EV-GGA) formalism, which optimizes the corresponding potential for band structure calculations. The calculated lattice constant, bulk modulus and electronic band structure of pseudocubic X3As4 (X=C, Si, Ge and Sn) compounds are in good agreement with other theoretical results. The analysis shows that the hardest material is C3As4 compound with a bulk modulus B0=106.5 GPa, while Si3As4, Ge3As4 and Sn3As4 have almost the same bulk modulus ranging from 51 to 68.5 GPa. Also we have presented the results of cohesive energies and we have given a detail discussion of the bond lengths and bond angles in the pseudocubic phase of group IV arsenides. Furthermore, band structure and density of states calculations show that Si3As4, Ge3As4 and Sn3As4 exhibit a semiconductor behavior with indirect gaps while C3As4 exhibit a metallic behavior using both GGA and EV-GGA.