QUANTUM MECHANICAL STUDY OF

The strategy of this work is based on the utility of the two international codes, GAUSSIAN 98 and CRYSTAL 98 to perform simulations of ionic crystals to clarify how the ab initio level of the quantum theory deals with the insulators.The former code, GAUSSIAN 98, was used to simulate LiH and AgBr crystals. The study of LiH aimed to compare the stabilities of the perfect- and defect-containing, (H-center), surfaces of the LiH crystals at different orientations; (110) and (111) in termsThe later code, CRYSTAL 98, was employed to simulate the alkaline-earth oxide-crystals; MgO, CaO and SrO at three different surfaces, namely; (001), (110) and (210). The simulation in this case was devoted to study some structural properties concerning th