water pressure in nanoscales

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1

hi， there！

i simulated the process of water molecules infiltrating into single-walled carbon nanotube.I tried to equilibrate the system, but it turned out a negative pressure no matter how small the timestep was and how big the total steps was.

surely i turned on the pairwise interaction between water and wall atoms.

have you experienced any similar situations ? i.e when did u come across negative pressure in water.

thanks in advance!

2

hi， there！

i simulated the process of water molecules infiltrating into single-walled
carbon nanotube.I tried to equilibrate the system, but it turned out a
negative pressure no matter how small the timestep was and how big the total
steps was.

surely i turned on the pairwise interaction between water and wall atoms.

have you experienced any similar situations ? i.e when did u come across
negative pressure in water.

there is too little tangible information here to make any definite statements.
negative pressure means, your "box wants to shrink". whether that is
physically meaningful or not is impossible to say in general.

axel.

3

If you are running fix nve or fix nvt i.e. constant volume, the pressure will assume a value consistent with the overall density. If that density is low, then the pressure will be negative. You can resolve this using a barostat e.g. fix npt, but there are lots of pitfalls, and you will need to learn quite a bit. I suggest reading some papers that describe how to simulate water and nanotubes in detail.

4

Thanks very much!