GEOC 69 |
| J. D. Kubicki, Department of Geosciences, The Pennsylvania State University, University Park, PA 16802 and A. V. Bandura, St. Petersburg State University, St. Petersburg, Russia. |
| Surface complexation models often must make assumptions regarding the atomic structure of the mineral-water interface. For example, the length of metal-oxygen bonds on the surface or the coordination state of an adsorbed ion may be assumed. Guided by information from potentiometric experiments and spectroscopic analyses (e.g., X-ray standing wave), ab initio calculations can help to better understand the fundamental picture input to the SCM calculations. In this study, periodic DFT energy minimizations were performed with H2O and Zn(II) adsorbed onto the (110) face of rutile using the program CASTEP. Water molecules were added to the hydrated crystal face in order to predict the relaxation of the surface Ti-O bonds. Zn(II) was modeled on the surface in a variety of configurations. Tetrahedral Zn resulted in model predictions most consistent with XSW spectroscopy. The structural information obtained from these calculations was then fed into SCM calculations of Machesky and coworkers. |
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Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
8:00 AM-11:40 AM, Tuesday, March 30, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |