Atoms moving too far while minimizing energy

Hi All,

I am trying to find a minimum energy configuration for a lattice. I am giving a text file with atom-id, type and x,y,z coordinates as input. After running the simulation for minimizing the energy using harmonic bonds and angles, I am using dump to output the final coordinates in a text file. But the difference between the initial and final coordinates are in some cases even more than 20 angstroms ! This is of course undesirable for a lattice to have such a huge deformation .

Can I set a limit for the overall maximum translation (not the maximum translation in a step) while doing the minimization, or is there any other solution to this problem ?

Thanks and Regards

Here is my LAMMPS script:

#----------- Initialize Simulation ---------------------
clear
units metal
dimension 3
boundary f f f
atom_modify sort 0 0
atom_style angle
bond_style harmonic
angle_style harmonic

#----------- Create Atoms ---------------------
read_data input.txt

#-------------Set dump-------------------------
dump myDump all atom 10000 result.txt
dump_modify myDump scale no

#-------------Run Minimization-----------------
reset_timestep 0
min_style sd
min_modify dmax 0.2
minimize 1e-25 1e-25 5000 10000

print “All done!”

input.txt (134 KB)

Hi All,

I am trying to find a minimum energy configuration for a lattice. I am
giving a text file with atom-id, type and x,y,z coordinates as input. After
running the simulation for minimizing the energy using harmonic bonds and
angles, I am using dump to output the final coordinates in a text file. But
the difference between the initial and final coordinates are in some cases
even more than 20 angstroms ! This is of course undesirable for a lattice to
have such a huge deformation .

Can I set a limit for the overall maximum translation (not the maximum
translation in a step) while doing the minimization, or is there any other
solution to this problem ?

the proper solution is to find out *why* this happens. not to suppress it.
most likely, there is something wrong with your potential parameters
or your data file.

axel.

Hi,

Thanks for the reply. There was indeed a mistake in the data file as some atoms were having same coordinates. Thanks for sharing your experience otherwise I would have been long lost in finding where exactly the error lies.