Self-consistent Hartree-Fock within the framework of large unit cell (LUC) formalism using complete and intermediate neglect of differential overlap (INDO) is used to simulate electronic band structure of covalent crystalline semiconductors. Correlation corrections are added via second-order Moller-Plesset perturbation method. Other corrections such as relativistic spin-orbit effects on the band gap and zero-point energy are also included. Cohesive energy, band gap, valence-band width, and hybridization orbitals are obtained from band calculations. Bulk modulus, charge distribution, and x-ray form factors are also calculated. These calculations are directed toward large scale or defected systems. Results show that the effects of some of these corrections are indispensable to obtain a clear view of semiempirical parameters used to fit band structure of covalent semiconductors. Correlation and INDO corrections removed some electronic cloud from the bonding region to the spherical region around the atom. Correlation corrections with its long time and limited improvements are not advised for large scale calculations. Solid parameters are compared with those of molecules and free atoms to understand the rules of parametrization in solids. Resemblance with size-dependent nanocluster properties is established for present calculations such as the decrease of band gap with increasing size of LUC. The major difference of the present calculations from previous nanocluster calculations is the use of the same element atom of the cluster to cap surface dangling bonds.