StevePugh.co.uk

PhD Thesis

My PhD research was carried out at the Computational Physics group, University of Keele, under the supervision of Professor Gillan. My thesis was submitted in December 1996, and examined in February 1997.

The title was:

First-principles simulation of molecular adsorption at oxide surfaces

Abstract

First-principles quantum mechanical calculations using density-functional theory and the pseudopotential method have been performed, in order to provide information on the interaction of two different metal-oxide materials with a variety of molecules. The calculations employ periodic boundary conditions, with the electronic wavefunctions described using a plane wave basis set. The total energy is minimised by adjusting the plane wave coefficients until the ground state is reached. All these methods are more fully described. The lattice parameters, surface energies and surface structure of magnesium oxide and titanium dioxide are calculated. The interaction of water and ammonia molecules with the MgO (001) surface, and of sulphur dioxide, sulphur monoxide, oxygen and methanol molecules with the TiO2 (110) surface are examined. The results provide information on the adsorption mechanism, energies, and geometry. It is found that the ammonia and water molecules are physisorbed on the MgO (001) surface and the most likely adsorption geometries are suggested. The oxygen and sulphur monoxide molecules react vigorously with the reduced TiO2 (110) surface, but the sulphur dioxide molecule less so. The methanol molecule is physisorbed on the stoichiometric TiO2 (110) surface, in molecular configurations only, which is in agreement with experiment.


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