[lammps-users] displace_box command and atoms concentration changing

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1

Dear,

When I do simulation in a periodic orthogonal box, I want to change the particle concentration through changing box volume . In manual, I find the displace_box command,

I want to know whether this command can do it. Thanks in advance.

2

Displace_box will do a one-time immediate change.
The fix deform command will make the change gradually
during a simulation run.

Steve

3

Hi,

Actually I also have same issue of increasing density and I am thinking of
compressing simulation box by fix deform, but I wonder whether that can give
rise to energy shoot-ups, since we will run it non-equilibrium way rather
than equilibrium way (as in decrease volume step by step but at each step
let system equilibriate)?

Thanks in advance!

Chetan

4

Chetan,

In terms of energy conservation, smaller, more frequent volume
adjustments would be preferable to larger more infrequent volume
adjustments. I see no problem with your using fix deform to gradually
compress your simulation box. Using N=1 is probably the best choice
since it will yield small, frequent volume adjustments.

Paul