The aim of this thesis is to use computer simulation methods to consider adsorption of both water and carbon dioxide onto oxide surfaces. The materials chosen have direct relevance to current environmental concerns, alkaline earth metal oxides for carbon sequestration and uranium dioxide for the storage and stability of nuclear materials. Chapter one outlines both previous experimental and computational work relevant to these research areas. The computational methodologies used in this thesis are described in chapters two and three. Chapter two outlines how the forces between atoms in the simulation are modelled using both potential-based and electronic structure models. Chapter three details how these are then used to find lowest energy configurations. The main results of the alkaline earth metal oxides are discussed in chapters four and five. Chapter four uses multiconfigurational static lattice simulations of water and CO2 surface adsorptions to identify the most probable adsorption sites and to generate surface phase diagrams as a function of surface composition. Whereas the focus of chapter five is to model interactions in liquid water with both surface and nanoparticles. Chapters six and seven describe the results of simulations on uranium dioxide. Chapter six uses electronic structure methods to model defects and nonstoichiometry in bulk and thin film structures. Chapter seven then describes the calculations of the interactions of water with uranium dioxide surfaces, in terms of both gas phase adsorption and the mineral – water interface with results showing the favourability of surface hydroxylation on the {100} and {110} surfaces. Finally, a summary of the main findings and achievements of this thesis are given in chapter nine, along with a discussion of possible future work.

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