Lardge, J.S.; (2009) Investigation of the interaction of water with the calcite {1014} surface using ab-initio simulation. Doctoral thesis , UCL (University College London).

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Abstract

Density functional theory calculations were employed to explore the interaction between water and the {1014} surface of calcite. In addition a defective {1014} surface and stepped surfaces in contact with water were investigated. A series of percentage water coverages and water con�figurations were explored, including dissociated water states. Static relaxations found associated water to be favourable on the {1014} surface, although a metastable dissociated state 1.77eV higher in energy was found. Molecular dynamics (MD) simulations of low water coverage reveal fluctuations in the H-O water bond when the H atom is directed towards a surface CO3 ion. Desorption of an H2O molecule was observed in simulations above 900K. Water was found to be strongly bound to the perfect {1014} surface, with an adsorption energy of -0.91eV. MD simulations of a defective {1014} surface found water to favour dissociation at CO3 vacancies. However, water at Ca vacancies di�used across the surface to form a bond with the nearest surface Ca ion. Water was also found to favour an associated state at both acute and obtuse steps. On all these imperfect surfaces water was found to adsorb strongly to the surface, with adsorption energies ranging from -0.99eV to -1.60eV.

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