Density functional theory (DFT) is the effective tool for investigation the electronic structure of various materials. In this work, we employed the DFT to study the effect of the skeleton conformation of 50% alternating SiTi copolymer polytitasilane to the electronic structure and the effect of the interaction strength between the metal-phthalocyanine molecules (MPc) and Al(100) surface on the shift of the vacuum level at the interface. In the first calculation, the polytitasilane electronic structure is depended on its conformation as implied from that by twisting the skeleton torsion from the trans-planar geometry to various helical conformations, the bandgaps are increasing accordingly.