GEOC 6 |
| Understanding soil processes at a molecular level is crucial for a systematic interpretation of the vast manifold of information available from experiments. The molecular processes are very complex, and much effort is being spent to understand them in detail using physical and chemical methods. Molecular modeling is a very powerful tool to get direct insight into molecular processes by means of computer simulations. This technique has already been in use in chemistry and molecular biology for a long time. The objectives of this work was to examine the possibility and investigate the limitations in studying the interactions of pesticides with soil constituents by means of molecular modeling techniques. Modeling the whole soil system in full complexity on a molecular level is practically impossible. Thus, one has to introduce several idealizations and simplifications for the construction of appropriate models. We have focused on several possible specific interactions on soil interfaces. Density functional theory (DFT) methods were used for the calculations. In real situations in soil solution, these subsystems will be surrounded by different kinds of environments, ranging from a polar to an unpolar character. Therefore, our main interest was directed towards the investigation of the dependence of interaction energies on the character of the environment (as described, for example, by the dielectric constant ƒ') into which these clusters were embedded. Results of these calculations will be presented and limitations of possible free energy calculation studies will be discussed. |
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Frontiers in Geochemistry: Commemorating the 25th Anniversary of the ACS-Geochemistry Division
9:00 AM-11:55 AM, Sunday, 10 September 2006 Moscone Center -- Room 262, Oral
Division of Geochemistry |