[lammps-users] "NPT" - Simulation Cell length

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1

Currently, I run my simulations using an anisotropic NPT, effectively compressing or expanding the simulation cell length in the z direction.
I am now looking at some materials where I am not concerned with the pressure of the system, but rather the density.
i.e. I wish to compress or expand the simulation cell in the z direction until I reach a particular length that gives me a simulation cell of volume which corresponds to the density that I am interested in, and then run an NVT simulation.

Is there any way of running simulation to compress the system to a required density within LAMMPS. I can't just run a series of NPT simulations at different pressures to try to determine which pressure would give me a simulation cell volume corresponding to the required density, as they are very slow to run and I have a large number of different materials which I am wishing to do this for. Any suggestions would be very helpful.

Thanks,
Michael Doig

2

Michael:

You might want to take a look at the “fix deform” command; it may do what you want, but you should check to make sure that it does so correctly.

–AEI

3

Dear Michael,

What I use is "fix deform". Once i get the correct dimensions, I unfix
it and run NVT.

Jan-Michael