Semiempirical self-consistent field calculations of III-V zinC-blende semiconductors.

The large unit cell (LUC) formalism within complete neglect of differential overlap (CNDO) frame is used to simulate three III-V compounds, zinc-blende type crystalline semiconductors. LUC used to investigate the three samples is eight times in size of primitive unit cell and constitutes (16) atoms per LUC. A computer program is prepared for this purpose on a PC computer. The LUC-CNDO equations implemented in this program. An iterative method is used to solve these uations. erties of BN, A1P and GaAs are obtained and compared with available experimental data and revious theoretical results. Semiempirical CNDO parameter sets for the three samples are deduced and used in the present work. Cohesive energy, direct and indirect band gap, hybridization state of the crystal orbitals are all obtained from valance band width and the band structure calculations at F, X and L high symmetry points in reciprocal space. Valance charge distribution and bulk modulus are, also, calculated. LUC-CNDO calculations showed a good agreement for cohesive energy and valance bandwidth with experimental data. A reasonable agreement for valance band eigenvalues and band gaps with experimental data have been obtained. Other properties showed a good trend compared to experimental values even when these values are not in a good agreement with the corresponding experimental values. This shows the possibility of using this method in qualitative survey at the early stages of materials design. The valance charge distribution calculations gave evidence on partially ionic-covalent bonding in this type of crystals, and the partial charge transfer values are calculated using Mulliken population
analysis.