[lammps-users] minimization problem.

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1

Hi ,

I want to know if it is possible to get a relaxed configuration with relaxed bounday lengths. For my minimization, I set an initial approximate boundary lengths (periodic box size) with the unrelaxed configuratrion and wanted to get a relaxed configuration with relaxed boundary lengths. I read the documentation for minimize command but it says that the volume of the simulation domain is not allowed to change during a minimization. Is there any alternate way to relax a structure along with its boundary? I did this type of relaxation with ParaDyn, however not sure how to do it with LAMMPS. is it possible to do it using ‘fix npt aniso’ command with zero desired pressure in all three direction?
Any suggestion is appreciated.

Thanks,
Ishraq Shabib

2

Dear Ishraq,
Yes, you can first minimize the system with fix boundary conditions and then use fix npt aniso command to relax the box dimensions independently.
I think it goes something like this

fix 1 all npt Tstart Tstop Tdamp aniso PstartX PstopX PstartY PstopY PstartZ PstopZ Pdamp

Regards,
Vikas