Unstable simulation of polarizable water and polarizable NaCl

LAMMPS LAMMPS General Discussion
1

Hi All,

I am trying to equilibrate a system of SWM4-NDP water and polarizable NaCl using the drude package. Even at timestep of 0.01 fs, I still get bond atoms missing between chlorine and its drude atom. Apparently, this is a problem that has been discussed here once in an old thread; something that may (or may not) have to do with overpolarization.

I have used bond_style table for chlorine as someone suggested in the thread. Still, doesn’t work. In fact, I got the table file from these researchers who had done the same simulation in LAMMPS and were somehow able to get it to be stable at 0.5 fs. Unfortunately, I can’t reproduce the work. I have used aggressive damping parameters in the NVT command since the temperature rapidly increases just before it crashes. I actually don’t know what else to try and need help with suggestions. Thank you very much!

I have attached the relevant files to this post for your perusal. Thanks once again.
Cl_bond_2A.dat (137.4 KB)
data.water+nacl-from-restart-run4 (4.1 MB)
in.equil-run5 (1.7 KB)
NaCl_SWM4_ndp.settings (516 Bytes)

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Have you started by trying to replicate the researchers’ script and results exactly?

If no, do that first. If yes, then there is a replicability problem here and you should correspond directly with them. I personally am skeptical that a polarizable simulation without Thole damping could ever work for a salt solution of that concentration. But, of course, it is the experiment that proves what is true or false.

1 Like
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Thank you very much for your response. I didn’t exactly replicate their work. What I mean by that is that I didn’t use the exact salt concentration they used because I didn’t think that this could play any real role in simulation stability (esp. at the concentration I am interested in). But I would definitely be doing that next as a test and see if I can reproduce the work. Thanks!