[lammps-users] Pressure is not stabilizing in MD simulation of water.

I am running MD simulation of water using spc/e model.
First i have done the minimization, after minimization presssure is negative( huge) then i gave temp of 300 by velocity command then i used fix npt as:
fix 1 all npt temp 300 300 100 iso 1 1 100
Temp is stabilized but pressure is still not comming to 1 bar and also there is huge fluctuation in the pressure till last step its far away from 1 bar… Please suggest a solution.

This is a topic that has been discussed on this very mailing list many times. I suggest you read through those old discussions before asking again.
Pressure fluctuates and it fluctuates more than temperature, and more for smaller systems and more for condensed systems and even more for not very compressible systems like water. Of course the pressure at the last MD step is useless under these circumstances. You need to look at averaged values (either spatially by running a larger system, or temporally by averaging over time or both). But this is all standard statistical thermodynamics stuff you should be discussing with your adviser/tutor/supervisor or experienced colleagues. a mailing list is not a classroom and you cannot expect to get the same kind of help from people here. you may get initially, but people patience wears thin quickly, if the person asking keeps asking about topics and issues that can be learned easily from other resources.