QUANTUM MECHANICAL STUDY OF ADSORPTION PROPERTIES AT THE SURFACES OF SOME SELECTED IONIC CRYSTALLINE SOLIDS

Abstract

The present thesis represents a theoretical study for the adsorption of some environmental gas pollutants namely; CO, NO, and CO2 and the possible factors affecting their adsorption on two different ionic soils belonging to the cubic system; MgO (100) and CdO (100) terraces. These factors include: (i) The nature of substrate; for this task the insulating MgO and the semiconductor CdO are used. (ii) The existence of the point –crystal-defects such as the neutral F and the positively charged F+ centers. (iii) The pre-adsorption of a single transition metal atom on the regular and the defective adsorption sites before the adsorption of the three gases CO, NO, and CO2. The utilized model in this thesis is the embedded cluster model using the Density Functional approach of theory with the help of the GAUSSIAN code. Results are discussed in terms of many aspects such as the geometrical parameters, adsorption energies, pair-wise and non pair-wise additivity, band gaps, Natural Bond Orbital analysis, Highest Occupied Molecular Orbitals as well as the Lowest Unoccupied Molecular Orbitals plots, electrostatic potential contours and finally the total charge density contours.