No i have membrane and water (but a little water for computational efficiency) and i have a sphere of iron oxide, and i am using pppm for long range interactions. i want to cross this sphere through the membrane , so in order to see the crossing throughly i have a big simulation box in z direction , and i was wondering should i barostat the pressure in z direction or not?
I see no reason not to barostate the pressure in the Z direction as well as the X and Y directions.
What Axel and I are both concerned about is that you were using the “iso” keyword. This will force the box to expand or contract by the same amount simultaneously in the X,Y,Z directions. That’s fine if you are simulating a liquid. But if your system is not symmetric in one or more of these directions (for example it is crystalline, or if you have a polymer spanning the X direction, or a membrane spanning the X and y directions), then you should use “aniso” instead.
See the documentation. It will help answer a lot of your questions:
https://lammps.sandia.gov/doc/fix_nh.html
Andrew
Thanks but i mean that by barostating the z direction it will shrink alot don’t you think?
Thanks but i mean that by barostating the z direction it will shrink alot don’t you think?
Perhaps I am not understanding your simulation, but I don’t see why this would happen.
Either way, I suggest that you try using “aniso” instead of “iso” and see if the results are still acceptable. (And also read the documentation, if you haven’t yet.)
Andrew