If I set the EDIFFG to be, for example, -0.01, how do I see the change in force from each ionic step? I tried look up force in the OUTCAR file, but so far to no avail. Anybody know exactly the right force/place to look at? Thanks.
If you use linux, execute this command:
grep 'TOTAL' OUTCAR -A number_of_atoms
will show you position and forces of every atom in every step.
Nope didn't work. This is what it responded
grep: number_of_atoms: invalid context length argument
It's okay I found it. I know which force you were trying to direct me to, but I thought there weren't right because some of them still more than 0.01 when my thing converged. Turns out all those that are more than 0.01 are the atoms I locked the position. Thank you tho.
One of the best way to use 'vtsttools' developed by Henkelman group. Install it first from here: http://theory.cm.utexas.edu/vtsttools/
After installation use 'vef.pl' or 'vef.py' command as described here: http://theory.cm.utexas.edu/vtsttools/scripts.html
In the output you will see how the max force and and energy converges in each ionic step as printed in a data file as well as in vector graphics (.eps) file. Enjoy!
Hi!
Another option is to use Peter Larsson's VASP tools:
https://www.nsc.liu.se/~pla/vasptools/
And in particular grad2. Easy to install and use. Give it a try!
Roberto
vasp outputs force on atoms after each ionic step. did you consider using NWRITE flag? http://cms.mpi.univie.ac.at/vasp/guide/node95.html .
"Turns out all those that are more than 0.01 are the atoms I locked the position" this is expected.
you should check the very last line after FORCE ACTING ON IONS that gives you total force acting on (in) crystal. this (total force, momentum) should be close to 0.
Am I too late here ? to use the attached txt change the extension to sh and make executable, or simply
$bash Fuerzas_por_atomo.txt
then handle the NIONS output files in whatever plotter you prefer. be sure to get the OUTCAR to the current directory. sorry for the spanish in the comments.
I just want to clarify a point made earlier by Fernando, and Thanaphong's confusion on the grep command. The number_of_atoms should be a number, not the string "number_of_atoms". Also, if you want the forces on all of your atoms, you should add 1 to this number. For example: if you have a calculation involving 4 atoms, then you should type
grep 'TOTAL' OUTCAR -A 5 ##this gives the forces of 4 atoms
If you want to print the drift as well, you need to add 2 to this value:
grep 'TOTAL' OUTCAR -A 7 ##this gives the forces of 4 atoms + the drift
So in general, number_of_atoms + 1 gives you all forces, and number_of_atoms + 3 gives you the forces and the drifts.
I don't know if it helps, but if you are using the right version (maybe 5.3), you can do
$grep "FORCES:" OUTCAR
for printing forces at each ionic step.
I generally use the following command to extract information from the OUTCAR file for each ionic step:
grep " in kB " OUTCAR
grep RMS OUTCAR I guess is what you need.
The first column gives the change in forces.
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