On Fri, Jun 5, 2009 at 11:58 PM, Jussi Lehtola <jussi.leht...@helsinki.fi>wrote:
> On Fri, 2009-06-05 at 23:28 +0530, Manik Mayur wrote: > > Hi, > > I am trying to equilibrate a box of SPC/E water using NVT simulations. > > After 2 ns of equilibration my pressure is still <0 bars. Is it an > > expected behavior for NVT simulations or the pressure should converge > > to the thermodynamic equilibration value corresponding to T and > > density after a finite time of equilibration? Can anyone point me to > > fundamental theory pertaining to this behavior as I couldn't find any > > upon googling. > > The pressure fluctuates quite a bit during the simulation and it is only > the average value you should look at. In your case the simulation length > is of course long enough to see what happens. > > Generally speaking, if your density is too small, the system wants to > increase it and thus you have negative pressure. If it is too large, > then the pressure is positive. Now you are running NVT, meaning that the > pressure can't be adjusted (it's done by scaling the simulation box), so > having a negative pressure is normal. Thanks for the insight. So if the density of my water system was corresponding to SPC/E water density at the given T, the pressure should have been themodynamically consistent? (I mean the average value of course.) > -- > ------------------------------------------------------ > Jussi Lehtola, FM, Tohtorikoulutettava > Fysiikan laitos, Helsingin Yliopisto > jussi.leht...@helsinki.fi, p. 191 50632 > ------------------------------------------------------ > Mr. Jussi Lehtola, M. Sc., Doctoral Student > Department of Physics, University of Helsinki, Finland > jussi.leht...@helsinki.fi > ------------------------------------------------------ > > > _______________________________________________ > gmx-users mailing list gmx-users@gromacs.org > 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 gmx-users-requ...@gromacs.org. > Can't post? Read http://www.gromacs.org/mailing_lists/users.php > Manik Mayur Graduate student Microfluidics Lab Dept. of Mechanical Engg. IIT Kharagpur INDIA
_______________________________________________ gmx-users mailing list gmx-users@gromacs.org 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 gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/mailing_lists/users.php
