Dear LIGGGHTS users,
I want to relax the packing system statistically by minimizing the energy, and used the command "minimize 1.0e-4 1.0e-6 10000 100000".
The error message is "Minimization could not find thermo_pe compute". The manual explains this error as "This compute is created by the thermo command. It must have been explicitly deleted by a uncompute command". But I have not deleted this compute.
In fact, I computed the system potential energy and output PE via the following commands: compute PE all pe, variable PE equal c_PE, thermo_style
custom v_PE. But it still reports the above error.
Could you please tell me how to solve this problem? Or Can LIGGGHTS do the same energy minimize as LAMMPS?
Thank you in advance!
Best wishes,
June
deepakpawar.2310 | Sat, 01/09/2021 - 18:08
I guess you can use the
I guess you can use the minimization command here in LIGGGHTS as well. But whole idea of using minimization command is to equilibrate the crystal system corrosponding
to its NVE, NVT or NPT ensemble in MD simulations..
since MD simulation typically involve the creation of crystal structure using the position and velocity of the atoms, afterwords the position derivative of interatomic potential
of each atom which gives the corresponding inter atomic force. Hence its necessary to check the equilibrium condition (using minimization command), which lead to the
time averaging of the output properties, which is the substantial property of the MD simulation
However, the working principle of MD and DEM is more a less same. the only difference in length scale In DEM, the whole granular assembly's kinetic energy is enough to ensure
that the system is entirely relaxed or not.
Hence in my view, it won't make much sense to use minimization command here in LIGGGHTS.
However, if you want to know more about the energy minimization.
Following lectures might helpful (specifically last week lessons)
https://onlinecourses.nptel.ac.in/noc20_me08/preview
Thank you
Happy learning !