Ab initio calculation of SiC polytypes

A systematic study of ground-state property of cubic and hexagonal silicon carbide polytypes (3C-, 6H-, 4H-, and 2H–SiC) is reported using the ultrasoft and norm-conserving pseudopotential methods of density-functional theory in the local-density approximation. The electronic and geometry structures of SiC polytypes are discussed in comparison with the experimental data. The conduction-band minimum with ultrasoft pseudopotential is the closest to (0.0,0.5,0.0) point as energy band calculation with several pseudopotentials. There is a marked discontinuity along ML line in the Brillouin zone with norm-conserving pseudopotential proposed by Lin. Both energy gap and valence-band width for the structure optimized with ultrasoft pseudopotential are greater than that with Lin’s. pseudopotential.