[lammps-users] how to re-set the box sizes after read_restart or read_data

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1

Hi, all,

Except in read_restart or read_data, how can I re-set the simulation box sizes?

For example, after running a long NPT simulation to equilibrate a
system, one wants to do simulation in an NVT ensemble with the
equilibrium volume (the average volume from the equilibrium snapshots
in the previous long-time NPT simulation). But the restart file from
NPT simulation does record the box sizes of last snapshot, how I
change the box sizes to the averaged lx, ly, lz?

Thanks in advance!

Dongshan

2

Hi, all,

Except in read_restart or read_data, how can I re-set the simulation box sizes?

For example, after running a long NPT simulation to equilibrate a
system, one wants to do simulation in an NVT ensemble with the
equilibrium volume (the average volume from the equilibrium snapshots
in the previous long-time NPT simulation). But the restart file from
NPT simulation does record the box sizes of last snapshot, how I
change the box sizes to the averaged lx, ly, lz?

please check out the displace_box command:
http://lammps.sandia.gov/doc/displace_box.html

cheers,
   axel.

3

Hi Axel,

Thanks for your reply. I used the following command for my system:
displace_box all x final -56.36841 56.36841 y final -58.5816325 58.5816325

But it comes out the error information:
ERROR: Use of displace_box with undefined lattice

So where is the error?

Best!

Dongshan

PS: My input script is as follows:

4

Hi Axel,

Thanks for your reply. I used the following command for my system:
displace_box all x final -56.36841 56.36841 y final -58.5816325
58.5816325

But it comes out the error information:
ERROR: Use of displace_box with undefined lattice

So where is the error?

sticking with the default of "units lattice" instead of using "units box"?

a.

5

You can use 'fix deform' instead:

fix 1 all deform 1 x final -56.36841 56.36841 y final
-58.5816325 58.5816325 z final zlo zhi units box

displace_box all x final -56.36841 56.36841 y final -58.5816325 58.5816325

Monojoy