Investigation of the Interaction of Water with the Calcite (10.4) Surface Using Ab Initio Simulation

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 configurations 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 CO 3 ion. Desorption of an H 2 O 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 CO 3 vacancies. However, water at Ca vacancies diffused 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.

Molecular interactions of SO2 with carbonate minerals under co-sequestration conditions: A combined experimental and theoretical study

“…5a) is uniform, showing the first layer of waters with their plane parallel to the surface, while any excess waters start forming a second layer with the O-H bond point towards the surface. The picture is consistent with previously reported results in literature, (De Leeuw and Parker, 1997;Kerisit et al, 2003;Rahaman et al, 2008;Lardge, 2009;Heberling et al, 2010) and it is reflected in the Ca-O w radial distribution function (RDF) of the top calcium atoms with the water oxygens, Fig. 5a, showing a sharp peak at 2.435 Å and a smaller one at about 4.5 Å .…”

“…On dolomite, SO 2 shows a clear preference for the calcium sites. The binding energies for water agree well with those reported in the literature, see for example work by Lardge (Lardge, 2009), which range between À0.63 to À0.91 eV depending on the binding site and water coverage. To our knowledge, the binding energies for SO 2 on calcite or dolomite are the first ones reported here.…”

Quantum Chemical Investigation of the Selenite Incorporation into the Calcite (101̅4) Surface

“…In the literature, see, [29][30][31] these calculations are called static optimizations compared to efforts explicitely including the motion of the involved species, as in molecular dynamic (MD) calculations. There are a lot of local energetic minima and almost certainly we did not find the global minimum.…”

“…We put an emphasis on the structural changes of pure calcite from the dry surface to the hydrated surface induced by the presence of water as well as the arrangement of the water layers adjacent to the surface. In the second part we studied the structural changes upon incorporation of selenite into the bulk phase and the dry and hydrated For this work we compared our results with the already available theoretical and experimental data of Aurelio et al, 21 Lardge et al, [29][30][31] Cheng et al, 45 Geissbühler et al, 47 Heberling et al 18,49 and Fenter et al 50,51 These studies have a similar focus as ours and provide a broad range of theoretical and experimental data to assess the accuracy of our results. This is important to ensure the accuracy of our results in every step of this work.…”

Reinterpreting edge energies calculated from crystal growth experiments

“…In contrast, Lardge determined g ¼ 90 erg=cm 2 using an ab initio model for a fully hydrated f1 0 1 4g surface of calcite [32]. Furthermore, Söhnel [33] and Christoffersen et al [34] list the bulk surface energies for calcite in water as g ¼ 97 erg=cm 2 and f e ¼ 2:38k b T, respectively.…”