Yes, that's exactly the article I had in mind!<br><br>There are also people studying stuff like dissociative hydration of, e.g., silica, they have some water models that can dissociate when needed, as well...<br><br><a href="http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/2003/3/i10/abs/nl034480e.html">http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/2003/3/i10/abs/nl034480e.html</a><br>
<a href="http://www.rsc.org/Publishing/Journals/DT/article.asp?doi=b516258k">http://www.rsc.org/Publishing/Journals/DT/article.asp?doi=b516258k</a><br><br><div class="gmail_quote">2008/4/28 David van der Spoel <<a href="mailto:spoel@xray.bmc.uu.se">spoel@xray.bmc.uu.se</a>>:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Vasilii Artyukhov wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
2008/4/28 Mark Abraham <<a href="mailto:Mark.Abraham@anu.edu.au" target="_blank">Mark.Abraham@anu.edu.au</a> <mailto:<a href="mailto:Mark.Abraham@anu.edu.au" target="_blank">Mark.Abraham@anu.edu.au</a>>>:<div>
<div></div><div class="Wj3C7c"><br>
<br>
Trying to model hydronium is a pretty flawed thing to do, since the<br>
hydrogens in real water are labile - so the molecule you'd label as<br>
"hydronium" moves much faster than any atoms do. <br>
<br>
I actually seem to remember reading something about some dissociative water models that could exchange protons between molecules, so that one could really have something like a pH in the simulation... doesn't really account for the quantum stuff like tunneling, though :)<br>
</div></div></blockquote>
<br>
<br>
@Article{ Mahadevan2007a,<br>
author = "T. S. Mahadevan and S. H. Garofalini",<br>
title = "Dissociative Water Potential for Molecular Dynamics<br>
Simulations",<br>
journal = "J. Phys. Chem. B",<br>
year = 2007,<br>
url =<br>
<br>
"<a href="http://pubs.acs.org/cgi-bin/abstract.cgi/jpcbfk/asap/abs/jp072530o.html" target="_blank">http://pubs.acs.org/cgi-bin/abstract.cgi/jpcbfk/asap/abs/jp072530o.html</a>",<br>
doi = "10.1021/jp072530o",<br>
abstract = "A new interatomic potential for dissociative water<br>
was developed for use in molecular dynamics<br>
simulations. The simulations use a multibody<br>
potential, with both pair and three-body terms, and<br>
the Wolf summation method for the long-range Coulomb<br>
interactions. A major feature in the potential is<br>
the change in the short-range O-H repulsive<br>
interaction as a function of temperature and/or<br>
pressure in order to reproduce the<br>
density-temperature curve between 273 K and 373 at 1<br>
atm, as well as high-pressure data at various<br>
temperatures. Using only the change in this one<br>
parameter, the simulations also reproduce<br>
room-temperature properties of water, such as the<br>
structure, cohesive energy, diffusion constant, and<br>
vibrational spectrum, as well as the liquid-vapor<br>
coexistence curve. Although the water molecules<br>
could dissociate, no dissociation is observed at<br>
room temperature. However, behavior of the hydronium<br>
ion was studied by introduction of an extra H+ into<br>
a cluster of water molecules. Both Eigen and Zundel<br>
configurations, as well as more complex<br>
configurations, are observed in the migration of the<br>
hydronium."<br>
}<br>
<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
<br>
------------------------------------------------------------------------<div class="Ih2E3d"><br>
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<br>
<br>
-- <br>
David van der Spoel, Ph.D.<br>
Molec. Biophys. group, Dept. of Cell & Molec. Biol., Uppsala University.<br>
Box 596, 75124 Uppsala, Sweden. Phone: +46184714205. Fax: +4618511755.<br>
<a href="mailto:spoel@xray.bmc.uu.se" target="_blank">spoel@xray.bmc.uu.se</a> <a href="mailto:spoel@gromacs.org" target="_blank">spoel@gromacs.org</a> <a href="http://folding.bmc.uu.se" target="_blank">http://folding.bmc.uu.se</a></font><div>
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