VASP practical tricks

Set up to run VASP from ASE

Refer to ASE VASP calculator doc: VASP Calculator

Execute command

ASE has to know the command to call and run vasp. This can be done by one of the following methods:

• Add an environment variable that contains the command to execute VASP.

    export ASE_VASP_COMMAND="mpirun vasp_std"
  

• Specify the command keyword in the Vasp calculator. This will overwrite the environment variable.

    calc = Vasp(command = "mpirun vasp_std")
  

• Alternatively, you can use the following script with the name run_vasp.py.

    import os
    exitcode = os.system("vasp")
  

  In this case, the environment variable VASP_SCRIPT must point to the above file.

Pseudopotentials

Pseudopotential directory has to be specified through the environment variable VASP_PP_PATH. You can set both environment variables in .bashrc:

export ASE_VASP_COMMAND="mpirun vasp_std"
# Alternatively, use something like this
#export VASP_SCRIPT=$HOME/vasp/run_vasp.py
export VASP_PP_PATH=$HOME/vasp/mypps

The following environment variable can be used to automatically copy the van der Waals kernel to the calculation directory. The kernel is needed for vdW calculations, see VASP vdW wiki, for more details. The kernel is looked for whenever luse_vdw=True.

export ASE_VASP_VDW=$HOME/<path-to-vdw_kernel.bindat-folder>

The environment variable ASE_VASP_VDW should point to the folder where the vdw_kernel.bindat file is located.

Check results

Convergence

Using tail

tail ./*/vasp.log

Tips for faster convergence

Final energy

grep --text "free  energy   TOTEN" OUTCAR | tail -1

Get the energy of a sequence of calculations:

list=not_converged.$(printf "%(%Y-%m-%d)T")
if [ -f "$list" ]; then
    > $list # Clear the content of the list.
fi
files=$(ls vasp.log.*)
for file in $files
do
echo ${file##*.}
done
for file in $files
do
name=${file##*.} # keep the last content after the last ".".
if grep -q "reached required accuracy - stopping structural energy minimisation" $file;
then grep "free  energy   TOTEN" OUTCAR.${name} | tail -1
else echo not_converged
echo $name >> not_converged.$(printf "%(%Y-%m-%d)T")
fi
done

Submit calculations that not converged

mapfile -t names < not_converged.$(printf "%(%Y-%m-%d)T")
for name in ${names[@]}
do
cp CONTCAR.${name} POSCAR
timeout 3h srun --distribution=block:block --hint=nomultithread vasp_std > vasp.log.${name}
mv OUTCAR OUTCAR.${name}
mv CONTCAR CONTCAR.${name}
mv OSZICAR OSZICAR.${name}
mv vasprun.xml vasprun.xml.${name}
done

NBANDS used in calculation

grep --text "NBANDS" OUTCAR