[lammps-users] displace_box command and atoms concentration changing


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.

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



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!



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.