2004 Denver Annual Meeting (November 710, 2004)
Paper No. 141-11
Presentation Time: 10:55 AM-11:10 AM


ASTHAGIRI, Aravind1, DOWNS, Robert T.2, and HAZEN, Robert M.1, (1) Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd NW, Washington, DC 20015, a.asthagiri@gl.ciw.edu, (2) Department of Geosciences, Univ of Arizona, 530 Gould-Simpson Building, Tucson, AZ 85721-0077

Hazen and coworkers have demonstrated that right- and left-handed calcite {214} surfaces preferentially select D- or L-aspartic acid, but what is the mechanism of selection? To answer this question we have applied density functional theory (DFT), an accurate first-principles method, to model chiral interactions between amino acids and chiral surfaces of calcite and quartz. DFT has been used to examine the adsorption of amino acids on chiral and achiral metal surfaces, but the extension to mineral surfaces is non-trivial since the mineral surface is more complicated and the calculations are correspondingly more computationally expensive. At the molecular scale, chiral selective adsorption of organic molecules onto a mineral surface requires three non-colinear points of interaction. Adsorption of amino acids likely involves bonding with the amino (NH2) group and the carboxyl (COOH) group. The orientation of these groups and the nature of the third interaction required for chiral selection are not known. In our initial work we examined the adsorption of alanine, the simplest chiral amino acid, on ideally truncated calcite {214} surfaces. We will report on our extensive calculations to map out the potential energy surface for both L and D-alanine on calcite (214). While these calculations are computationally intensive, they yield detailed quantitative information on the energetics and structural details of adsorption that are not readily accessible through experiments.

2004 Denver Annual Meeting (November 710, 2004)
General Information for this Meeting
Session No. 141
Looking Forward to the Past: A Session in Honor of Paul Ribbe and the Reviews in Mineralogy and Geochemistry II
Colorado Convention Center: 708/710/712
8:00 AM-12:00 PM, Tuesday, November 9, 2004

Geological Society of America Abstracts with Programs, Vol. 36, No. 5, p. 338

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