Modeling ligand exchange on an aluminum oxide molecular cluster from first principles

COLL 457

Andrew Gregory Stack, andrew.stack@eas.gatech.edu, School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, GA 30309, James Rustad, Department of Geology, University of California Davis, One Shields Avenue, Davis, CA 95616, and William H. Casey, Department of Chemistry and Department of Geology, University of California, 350 Chemistry Bldg, Shields Avenue, Davis, CA 95616.
Ligand exchange is often a controlling factor for a variety of environmentally important reactions, including mineral growth and dissolution. However, difficulty in characterizing the ligand exchange rates on surfaces has inspired us to develop predictive models using more easily characterized substances that contain functional groups similar to those of common soil minerals. Using a combination of molecular dynamics (MD) simulations and ab initio calculations, we model first-shell water exchange on an aluminum polyoxocation. Solvent structure and initial state for the exchange are inferred from the MD simulations, while the ab initio calculations give precise energetics. The calculated energy difference between the initial and transition states is +53 kJ/mol, close to the experimental estimate of +63 kJ/mol.
 

Environmental Interfaces
8:30 AM-12:40 PM, Wednesday, 13 September 2006 Sir Francis Drake -- Empire Room, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006