Polarizable water model in a non-periodic box

LAMMPS LAMMPS General Discussion
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1

Hi All,
I am working on a system of swm4-ndp water model in a channel. As a start, I followed the LAMMPS tutorial in the drude package for simulating the bulk with periodicity in all directions. Everything works fine. Now, I’m confining the water between upper and lower walls of atoms in an fcc lattice. So the box is non-periodic in z-direction. Now, this is the challenge I face and where I need your help:

variable TK equal 300.0
variable TDK equal 1.0
variable PBAR equal 1.0

fix TEMP all langevin/drude ${TK} 100. 1256 ${TDK} 20. 13977 zero yes
 fix NPH ATOMS rigid/nph/small molecule iso ${PBAR} ${PBAR} 100

These the command to use for an NPT simulation. But since I will be running an NVT simulation in my case here, I don’t know how to go about it. The rigid/nvt/small is my natural choice but cannot be used with fix langevin. The fix langevin is already thermostating the core and drude particles. So, I don’t know what commands or LAMMPS strategy to use here. I’ll appreciate some advice. Thanks.

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First off, I had to correct your quoted input to wrap it with triple quotes (```) so it displays correctly with the forum software using markup (please see the forum guidelines post for details on that). In future posts, please make sure your quoted file segments are properly quoted and thus readable, since not everybody has sufficient forum permissions to make your posts readable.

The closest to your previous setup would be to change the line from above to:

fix NPH ATOMS rigid/nph/small molecule x ${PBAR} ${PBAR} 100 y ${PBAR} ${PBAR} 100 couple xy

Or if you don’t want to change the box dimensions in x and y:

fix NPH ATOMS rigid/nve/small molecule

3

Thank you very much Axel.

I will take into account the posting guideline next time. And I will try out your suggestions.Thanks.