[lammps-users] instantaneous expansion

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1

Hi everyone,

I want to make silica aerogel. According to this article’s procedure (https://doi.org/10.1021/acs.jpcb.7b03184), there is a need for instantaneous expansion after making amorphous silica.

Unfortunately, I do not understand how to apply instantaneous expansion in the LAMMPS.

I listed the steps below:

  1. heated to 7000 K (NVT ensemble)

  2. Quench to 300 K (NVT ensemble) + conjugate gradient minimization

  3. Relaxing structure @ 300 K and 1bar (NPT ensemble)

  4. relaxed at 300K for 7.5 ps followed by instantaneous

expansion to the desired density.

  1. Heated to 3000 K for 50 ps(NPT ensemble)

  2. Quench to 0 K (NVT ensemble) + conjugate gradient minimization

  3. Relaxing @ 300 K and 1bar (NPT ensemble)

I would be very grateful if someone could guide me.

Best regards,

Ali

1 Like
2

Please look at the documentation for the change_box command. That is truly instantaneous (even beyond what is physically possible in an experiment). Or at fix deform, which allows to set the rate of expansion.

Axel.

3

Thank you Axel.
I will work on it.