How do I do energy minimization in lammps with NVT ensemble ?
I am using the following command and it does not seem to work. It stops at extremely high energy and gives me the error zero search line alpha. I am using the following command.
# initial minimization
fix 1 mobile nvt temp 315.00 315.00 100.0
min_style sd
minimize 1.0e-10 1.0e-10 200000 200000
write_data 100PU_water.minimized
unfix 1
What am I doing wrong ? If I use min_style as quickmin it runs for the entire duration but does not work in SD. Most importantly I need to do it in NVT. How do I do that ?
Thank you
Good afternoon!
There are 'run' and 'minimize' commands. The commands can be used one at a time. They can't be used at the same time. First one thing, then another. Not together.
You should add the run command after the fix.
When studying science, the examples are more useful than the rules!(Isaac Newton)
Code LAMMPS Script for the generation of Grain Boundaries(GB) Ni(...
LAMMPS:
"Minimize commands can be interspersed with run commands to alternate between relaxation and dynamics. The minimizers bound the distance atoms move in one iteration, so that you can relax systems with highly overlapped atoms (large energies and forces) by pushing the atoms off of each other.
Alternate means of relaxing a system are to run dynamics with a small or limited timestep. Or dynamics can be run using fix viscous to impose a damping force that slowly drains all kinetic energy from the system. The pair_style soft potential can be used to un-overlap atoms while running dynamics. un-overlap atoms while running dynamics."
Misha Urazaliev I understand that run and minimize cannot be used at the same time. What I do want to know is, if there is a way to do the minimization process under NVT ensemble. I know that minimization might not always work as expected but we would need to use the right modifiers and style. I just need to know if there is a way to use NVT ensemble to do minimization.
Thank you
Hi, I can't understand exactly what you mean by minimizing energy in NVT ensemble. But I would suggest you to minimize the energy using minimize command first. Then try relax the structure in NVT ensemble. Your script should look something like this:
min_style sd
minimize 1.0e-10 1.0e-10 200000 200000
timestep XXXXX
thermo XXXX
fix 1 mobile nvt temp 315.00 315.00 100.0
run XXXX
write_data 100PU_water.minimized
However, you need to carefully select (read some literature) appropriate timestep and simulation time for a fully equilibrated system.
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