Theoretical investigation of the water/corundum (0001) interface

Abstract

For the reliable long-term modeling of the actinide migration in geological formations, the adsorption/desorption properties and the reactivity of mineral surfaces must be understood at the molecular level. The adsorption of radioisotopes at mineral surfaces of the aquifer is an important process that leads to the retention of contaminants such as radionuclides. Their transport by the ground water is either retarded or even completely inhibited by the presence of such a surface. Accordingly, this subject is of main importance for the safety assessment of nuclear waste repositories. As part of a joint theoretical/experimental effort, the interaction of water with the corundum (0001) surface is studied using several theoretical methods (Moller-Plesset perturbation theory, coupled cluster singles doubles with triplet corrections, as well as density functional theory). We focus in this study on the determination of the bond lengths and tilt angles of the surface OH species and their respective vibrational frequencies. The theoretical results are confirmed by subsequent simulation of the interface selective nonlinear sum frequency spectra. The excellent agreement of the simulated with the experimental spectra allows an assignment of the observed peaks in the sum frequency spectra of the water/corundum (0001) interface on the basis of our theoretical data. In this theoretical study we are able to give a unique interpretation of the observed sum frequency spectra of the water/corundum (0001) interface.

Quantum chemical study of inner-sphere complexes of trivalent lanthanide and actinide ions on the corundum (0001) surface

“…We employed the same methodology as in our recent theoretical paper [6], where we showed that the RI-DFT method [15][16][17][18][19][20] as implemented in the TURBOMOLE program package [16][17][18][19][21][22][23] provides very accurate results for this class of systems. It turned out, that the BP86 functional [10][11][12][13][14] together with the cc-pVDZ basis set [24] is the optimal combination of functional and basis set for our purpose [6].…”

“…[6] and references therein and for the interaction of uranyl see [7][8][9], but to best of our knowledge there are no theoretical calculations dealing with the sorption of trivalent actinide/lanthanide ions on mineral surfaces.…”

“…We focused in this quantum chemical study on the structure of the inner-sphere complexes of trivalent lanthanide and actinide ions at the corundum (0001) surface by using the cluster model, as introduced in our previous study [6]. With this model we investigated the interaction of the metal ions with the surface by adding the solvated metal ion on top of the Al 31 O 60 H 21 cluster [6].…”

“…With this model we investigated the interaction of the metal ions with the surface by adding the solvated metal ion on top of the Al 31 O 60 H 21 cluster [6]. This model allowed us to study the structure of the inner-sphere complex at the corundum (0001) surface and to find the energetically most likely structure depending on, firstly, the number of protons H + removed from the surface and, secondly, the number of water molecules remaining in the first coordination shell.…”

Size distribution of associated clusters in liquid alcohols: Interpretation of simulation results in the frame of SAFT approach

“…Nevertheless, these methods significantly contributed to the interpretation of the spectroscopic measurements and to the understanding the mechanism of the cooperativity of the hydrogen bonding. [21][22][23][24] The classia) Email: janecek_jiri@centrum.cz b) Email: patrice.paricaud@ensta-paristech.fr cal atomistic simulations can treat much larger systems (compared to quantum methods) and thus they represent important tool to study the internal structure of associating systems. Several recent as well as classical studies were aimed to analyze the size and topology of associated species.…”