In addition, we also tried to equilibrate the liquid-gas interface in the NVT and then switched on barostat. The result with barostat was unfortunately the same. I suspect the problem is in the (anisotropic) pressure coupling but I still have no idea how it can be corrected. The described setup is taken for the literature where it is reported to be successful.
Vitaly ---------- Forwarded message ---------- From: Vitaly Chaban <[email protected]> Date: Mon, Jul 12, 2010 at 10:59 PM Subject: dissolution of gases in liquid To: [email protected] Hi all, We are trying to calculate the solubility of argon in water using the partial densities function. The following traditional MD setup is used. The water (=4000) is in the center of the box and is surrounded by the argon atoms (=50) along Z direction. The electrostatics is treated with PME, the LJ - with a shifted force method, the cut-offs are 0.9nm. The Parrinello-Rahman barostat is applied in Z direction only. Water and gas are coupled separately to 298K. The FFs are OK both for water and argon separately. In the NPT, a rather strange result is obtained (please see a plot) - http://yfrog.com/3mdissolj The argon atoms and the water molecules are distributed uniformly in the box and this results in the unphysically big solubility of argon. We tried also NVT (please see the above plot, http://yfrog.com/3mdissolj) and got a better situation. This one is rather physical if one considers the pressure which occurs in such setup. The question is WHY NPT gives so weird results? I would like to get the dependence of the solubility vs pressure, thus I am interested in NPT mostly. Does anybody have any insights? Vitaly Dr. Vitaly Chaban -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to [email protected]. Can't post? Read http://www.gromacs.org/mailing_lists/users.php
