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. -- ------------------------------------------------------ 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
