Chemical & Materials Sciences Division
Staff Awards & Honors
April 2007
Kathmann, Schenter, and Garrett Have Letter Selected for Virtual Nanoscale Journal
Congratulations to Pacific Northwest National Laboratory's Shawn Kathmann, Gregory Schenter, and Bruce Garrett on having their comment letter from Physical Review Letters selected for the March 26, 2007, issue of Virtual Journal of Nanoscale Science & Technology. The journal, published by the American Institute of Physics and the American Physical Society in cooperation with others, provides links to articles on the frontier of nanoscale research and development.
In their letter, the three authors underscored the importance of anharmonicity that was neglected in the work of Nadykto et al.. The article by Nadykto et al. computed the free energies for clusters containing a single ion surrounded by several water molecules using a single minimum energy configuration for each size cluster.
The PNNL team showed that a more robust approach, sampling hundreds of millions configurations for each aqueous ionic cluster, is necessary to obtain accurate energy calculations. This more complete configurational sampling is needed because a great many of the relevant ion/water configurations are not global minima. This effect is termed anharmonicity, and it can have a profound influence on the computed free energies.
Why does it matter? Water/ion interactions are ubiquitous in nature. For example, to better understand and reduce aircraft contrails, the long line-shaped clouds that form behind a jet engine, government agencies and manufacturers must understand the thermodynamics of water molecules clustering around ions generated in the combustion process. In addition, these clustering reactions are important in understanding the mechanisms of electrospray ionization.
