Some General Points to Remember when Running VASP Calculations

To visualize and modify your structures you can use VESTA: https://jp-minerals.org/vesta/en/download.html

For more instructions about VESTA you can use: https://www.youtube.com/channel/UCmOHJtv6B2IFqzGpJakANeg/videos

As explained below, VASP calculations require 4 input files: INCAR, KPOINTS,  POSCAR, and POTCAR. 

One needs to create a separate directory for each calculation and copy the input files to the directory. A brief introduction to the files: 

(1) INCAR: All calculations set ups such as energy and force convergence, single point energy calculation, optimization, or MD; 2D vs 3D calculations etc. are defined here. Most keywords are explained (commented). If you want to know about a particular keyword you could search for it in VASP WIKI documentation. Just type the word and VASP in google and it will take you to many online sources explaining it. VASP has been popular among researchers for many years. So, it is easy to find the explanations from online groups. 

(2) POSCAR: We define atomic positions and lattice vectors here. Note that the atomic positions are in crystal units. To convert it, I usually open the file in VESTA and export again as a POSCAR file, but now in angstrom unit. I don't have a script to automate it. But, will be useful when planning to run several calculations in one go.  

(3) KPOINTS; Typically I use gamma-point centered high symmetry points in Brillouine zone. Monkhorst-Pack grids. You may change it according to the problem. 

(4) POTCAR: Potential files are distributed along with the VASP software and license. I use GGA-PBE PAW pseudo potentials. This is saved as default POTCAR file in the VASP pseudopotential directory in hpc. Once you open POTCAR file, you could see the explanation in the first few lines. 

If the system has more than one unique element, you need to copy the POTCAR file for each element and concatenate all of them in the same order as you have it in POSCAR file. To highlight the difference for a system with more than one unique element, I have attached a file named POSCAR_2. 

type module show to get the path for vasp installation and pseudopotential (POTCAR) files.

I feel PBE PAW pseudopotentials should be good for most purposes. Test different convergence criteria for your system before starting the production run. 

To concatenate POTCAR files, use the command, cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR >POTCAR (this also shows that you don't need to coy all POTCAR files into the working directory. Instead, you could directly create the final POTCAR file in one go). 

(5) I haven't exported the wave functions files from VASP for any specific purpose. So, I cannot help you with that for now. But, you may check online for guidance. 

VASP creates a lot of scratch files. So, it can use all the memory very quickly. If you need to run many calculations in one go, plan ahead to delete unnecessary files.

Required Input Files 

VASP needs 4 input files to run.  INCAR, POSCAR, POTCAR, and KPOINTS.
If you want an example of all the files needed to run a test calculation, you can download them from here. 

 
However, below is an example of VASP input files, just in case the link above does not work.

1. INCAR

# INCAR file

SYSTEM = graphene

# Hamiltonian

# LDA calculation is the default one?

# GGA calculation

GGA = PE

NCORE=8  # equal to the Number of core each nodes for better calculation speed

# vasp 5.2.11 setting

LREAL =.FALSE.   accurate energy calculation

#PREC = Med    precision of calculation

NELM = 60     max number of 1SCF  cycles

EDIFF = 1E-04   stopping criterion

ISMEAR = -5    big crystal use 0, default -5 for insulator and semiconductor

#SIGMA= 0.005   small for insulator

#ALGO = Very Fast

ISPIN = 2

# run from scratch

ISTART =   0 # starts from scratch, 

ICHARG =   1

#INIWAV =   1

# run from checkpoint

#ISTART = 2

# no. of bands

#NBANDS = 944    for primitive cells !

#NUPDOWN = 0

# Electronic relaxation

# usual basis size

ENCUT =   600.00 eV  plane wave cut-off

ENAUG =   1200.00 eV  charge augmentation cut-off

# Ionic relaxations

NSW =  0          max number of movements

IBRION = 2

ISIF = 3

NELMIN =3

EDIFFG = -2E-03

# Other parameters

ISYM = 2            soft symmetrization

NWRITE = 2          most of the important information is written

SYMPREC = 0.001

# vdw interactions

IVDW= 12  # Van der Waals dispersion D3 with BJ damping. Available in VASP 5.3 or newer

2. POSCAR

Graphene POSCAR

1.00000000000000

2.4670806653457333 0.0000000000000000 0.0000000000000000

1.2335403326728667 2.1365545293748203 0.0000000000000000

0.0000000000000000 0.0000000000000000 14.0000000000000000

C

2

Direct

0.3333333333333357 0.3333333333333357 0.5000000000000000

0.0000000000000000 0.0000000000000000 0.5000000000000000

3  KPOINTS

Automatic mesh

0              ! number of k-points = 0 ->automatic generation scheme

Gamma           ! fully automatic: MP-set

 15  15  1       !

4. POTCAR

We need to cat all the pseudopotential of all atoms in the POSCAR into file POTCAR. 

In the HPCC, the POTCARs will be in:

/mnt/research/mendozacortes_group/VASP6/potpaw_LDA.54.tar_0_2.gz or 

                                     /potpaw_PBE.54.tar_0_0.gz
You will need to unzip these tarball

e.g. /opt/software/VASP/6.2.1-intel-2020b/pot/PBE
or for example if the path for the potentials are in ~:

cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR >POTCAR

or more info at: 
https://www.vasp.at/wiki/index.php/POTCAR

Useful Scripts

Please copy these scripts from /mnt/home/djokicma/bin 

Once these are all set up you can also easily access the scripts by creating an alias in your bashrc:

# Scrips for VASP 

alias POTCAR_create_from_POSCAR='~/bin/POTCAR_create_from_POSCAR' 

alias mkdir_VASP='~/bin/mkdir_VASP' 

alias POTCAR_create='~/bin/POTCAR_create'

1. mkdir_VASP

This is a script which will automate the creation of the whole input folder, prompting the user for details of the calculation. 

In order to use this script, please make sure that scripts 1, 2, and 3 are setup with appropriate paths, including a template folder which can be copied from  /mnt/home/djokicma/VASP/Standard, and a POTCAR folder from /mnt/home/djokicma/VASP/References/POTCARs

#!/bin/bash

any_int='^[0-9]+$'

any_int_range='^[0-9]+-?[0-9]*$'

FinalReminder="Reminders:\n"

UserInputHistory=""

BadInput="I do not know how to interpret this input. Script terminating."

StandardInputFileDirectory="/mnt/home/djokicma/VASP/Standard"

echo -n "Do you want to use your current directory? (1/0) "

read -n 1 UseThisDir ; echo ""

UserInputHistory="${UserInputHistory}${UseThisDir}"

if [ "$UseThisDir" == 1 ]; then

        MyDir=$PWD

elif  [ "$UseThisDir" == 0 ]; then

        # The following lines have unexpected behavior:

        # 1) If there are no subdirectories it produces a ls error message

        # 2) If you press enter without specifying a new directory, the rest of the script doesn't work

        # Update 2021/12/1: I believe I fixed the above unexpeced behavior. Delete these comments if no issues appear by 2022/1/1

        ChildDirectoryCount=$(find $PWD -mindepth 1 -maxdepth 1 -type d | wc -l)

        if [ "$ChildDirectoryCount" -gt 0 ]; then

                echo "For reference, the subdirectories in your current directory are: "

                ls */ -d

        else

                echo "There are no subdirectories in your current directory."

        fi

        echo -n "Specify a new or existing directory: "

        while [ -z "${MyDir}" ]; do 

                read -e MyDir

                UserInputHistory="${UserInputHistory}${MyDir}\n"

        done

        if [ ! -d "$MyDir" ]; then

                echo "$MyDir does not exist. Creating now."

                mkdir $MyDir

        fi

        cd $MyDir

else

        echo $BadInput

        exit 1

fi

echo "The working directory is $MyDir"

parent=$(dirname $PWD); parent="${parent##*/}"

MyDirPretty="${MyDir##*/}"

ParentTitle="$(grep -s "JOB=" ../submission.slurm | cut -f 2 -d = )"

CurrentTitle="$(grep -s "JOB=" submission.slurm | cut -f 2 -d = )"

echo "Title suggestions: ${parent}_${MyDirPretty} ${ParentTitle}_${MyDirPretty} ${CurrentTitle}"

echo -n "What is the title of this calculation? "

read -e Title

UserInputHistory="${UserInputHistory}${Title}\n"

if [ "$Title" == 1 ]; then

        Title="${parent}_${MyDirPretty}"

elif [ "$Title" == 2 ]; then

        Title="${ParentTitle}_${MyDirPretty}"

elif [ "$Title" == 3 ]; then

        Title="${CurrentTitle}"

fi

echo "The Title is $Title"

# POSCAR section

if [ -f "POSCAR" ]; then

        echo -n "Do you want to use the POSCAR already in ${MyDir}? (1/0) "

        read  -n 1 UseThisPOSCAR ; echo ""

        UserInputHistory="${UserInputHistory}${UseThisPOSCAR}"

        if [ "$UseThisPOSCAR" == 1 ]; then

                MyPOSCAR="POSCAR"

        elif [ "$UseThisPOSCAR" != 0 ]; then

                echo $BadInput

                exit 1

        fi

else

        UseThisPOSCAR=0

fi

if [ "$UseThisPOSCAR" == 0 ]; then

        echo -n "Specify a path to a POSCAR: "

        read -e MyPOSCAR

        UserInputHistory="${UserInputHistory}${MyPOSCAR}\n"

        if [ ! -f "$MyPOSCAR" ]; then

                echo "Cannot find a POSCAR at ${MyPOSCAR}. Script terminating."

                exit 1

        fi

        cp $MyPOSCAR ./POSCAR

fi

sed -i "s/^M//g" POSCAR

sed -i "1 s/^.*$/${Title}/" POSCAR

# POTCAR section

~/bin/POTCAR_create_from_POSCAR

mv POTCAR_* POTCAR

# INCAR section

if [ -f "INCAR" ]; then

        echo -n "Do you want to use the INCAR already in ${MyDir}? (1/0) "

        read  -n 1 UseThisINCAR ; echo ""

        UserInputHistory="${UserInputHistory}${UseThisINCAR}"

        if [ "$UseThisINCAR" == 1 ]; then

                MyINCAR="INCAR"

        elif [ "$UseThisINCAR" != 0 ]; then

                echo $BadInput

                exit 1

        fi

else

        UseThisINCAR=0

fi

if [ "$UseThisINCAR" == 0 ]; then

        echo "Select a standard INCAR or non-standrd INCAR format."

        echo -n "(4:EFIELD / 3:Bader / 2:single-point / 1:standard / 0:non-standard format) "

        read -n 1 UseStnINCAR ; echo ""

        UserInputHistory="${UserInputHistory}${UseStnINCAR}"

        if (( "$UseStnINCAR" >= 1 && "$UseStnINCAR" <= 4 )); then

                MyINCAR="${StandardInputFileDirectory}/INCAR_Standard"

        elif  [ "$UseStnINCAR" == 0 ]; then

                echo -n "Specify a path to an INCAR: "

                read -e MyINCAR

                UserInputHistory="${UserInputHistory}${MyINCAR}\n"

                if [ ! -f "$MyINCAR" ]; then

                        echo "$MyINCAR does not exist. Script terminating."

                        exit 1

                fi

        else

                echo $BadInput

                exit 1

        fi

        cp $MyINCAR ./INCAR

        sed -i "s/^SYSTEM .*/SYSTEM = ${Title}/" INCAR

        if [ "$UseStnINCAR" == 4 ]; then

                echo -n "Provide the electric field along the slab axis in eV/Å: "

                read EFIELD

                UserInputHistory="${UserInputHistory}${EFIELD}\n"

                sed -i "s/.*EFIELD_HERE.*/EFIELD = $EFIELD/" INCAR

                sed -i "s/.*IDIPOL_HERE.*/IDIPOL = 3/" INCAR

                sed -i "s/^LDIPOL.*/LDIPOL = \.TRUE\./" INCAR

                sed -i "s/^LAECHG.*/LAECHG = \.TRUE\./" INCAR

                FinalReminder="${FinalReminder}> You have applied a uniform electric field along lattice vector #3 (aka the z-axis).\nThis selection is only valid if this system is a slab normal to the z axis.\nIf this does apply, you need to change IDIPOL manually.\n"

        elif [ "$UseStnINCAR" == 3 ]; then

                sed -i "s/^LAECHG.*/LAECHG = \.TRUE\./" INCAR

        elif [ "$UseStnINCAR" == 2 ]; then

                sed -i "s/^NSW.*/NSW    = 0/" INCAR

        fi

        if (( "$UseStnINCAR" >= 1 && "$UseStnINCAR" <= 4 )); then

                echo -n "Keep the precision 'Normal' rather than increasing to 'Accurate'? (1/0) "

                read -n 1 NormalAccuracy ; echo ""

                UserInputHistory="${UserInputHistory}${NormalAccuracy}"

                if [ "$NormalAccuracy" == 0 ]; then

                        sed -i "s/^PREC.*/PREC  = Accurate/" INCAR

                        echo "Updating INCAR for higher precision."

                elif [ "$NormalAccuracy" != 1 ]; then

                        echo $BadInput

                        exit 1

                fi

                echo -n "Keep the normal step size (POTIM=1) and do not reduce step size (to POTIM=0.2)? (1/0) "

                read -n 1 NormalStepSize; echo ""

                UserInputHistory="${UserInputHistory}${NormalStepSize}"

                if [ "$NormalStepSize" == 0 ]; then

                        sed -i "s/^POTIM.*/POTIM  = 0\.2/" INCAR

                        echo "Updating INCAR for smaller step size."

                elif [ "$NormalStepSize" != 1 ]; then

                        echo $BadInput

                        exit 1

                fi

        fi

fi

sed -i "1 s/^.*$/${Title}/" INCAR

# KPOINTS section

if [ -f "KPOINTS" ]; then

        echo -n "Do you want to use the KPOINTS already in ${MyDir}? (1/0) "

        read  -n 1 UseThisKPOINTS ; echo ""

        UserInputHistory="${UserInputHistory}${UseThisKPOINTS}"

        if [ "$UseThisKPOINTS" == 1 ]; then

                MyKPOINTS="KPOINTS"

        elif [ "$UseThisKPOINTS" != 0 ]; then

                echo $BadInput

                exit 1

        fi

else

        UseThisKPOINTS=0

fi

if [ "$UseThisKPOINTS" == 0 ]; then

        echo -n "Do you want to use the standard KPOINTS format? (1/0) "

        read  -n 1 UseStnKPOINTS ; echo ""

        UserInputHistory="${UserInputHistory}${UseStnKPOINTS}"

        if [ "$UseStnKPOINTS" == 1 ]; then

                MyKPOINTS="${StandardInputFileDirectory}/KPOINTS_Standard"

        elif  [ "$UseStnKPOINTS" == 0 ]; then

                echo -n "Specify a path to a KPOINTS: "

                read -e MyKPOINTS

                UserInputHistory="${UserInputHistory}${MyKPOINTS}\n"

                if [ ! -f "$MyKPOINTS" ]; then

                        echo "$MyKPOINTS does not exist. Script terminating."

                        exit 1

                fi

        else

                echo $BadInput

                exit 1

        fi

        cp $MyKPOINTS ./KPOINTS

fi

if grep -q "KA" KPOINTS; then

        # The number of kpoints recommended will be chosen such that this number * the lattice constant ~= stand_prod (standard product)

        stand_prod=39.0

        read -r scale_factor ax ay az bx by bz cx cy cz <<< $(echo `sed '2,5!d' POSCAR | grep -Eo '[0-9\.]+'`)

        a=`echo "$scale_factor * sqrt($ax^2+$ay^2+$az^2)" | bc`

        b=`echo "$scale_factor * sqrt($bx^2+$by^2+$bz^2)" | bc`

        c=`echo "$scale_factor * sqrt($cx^2+$cy^2+$cz^2)" | bc`

        # unrounded calculation first

        ka0=$(echo "scale=3; $stand_prod/$a" | bc)

        kb0=$(echo "scale=3; $stand_prod/$b" | bc)

        kc0=$(echo "scale=3; $stand_prod/$c" | bc)

        # round with preference towards rounding up (to be safe)

        roundingFactor=0.9 # exceed stand_prod in approx this fraction of the domain

        ka=$(echo "scale=0; ($ka0+$roundingFactor)/1" | bc)

        kb=$(echo "scale=0; ($kb0+$roundingFactor)/1" | bc)

        kc=$(echo "scale=0; ($kc0+$roundingFactor)/1" | bc)

        ka=$((ka>1 ? ka : 1))

        kb=$((kb>1 ? kb : 1))

        kc=$((kc>1 ? kc : 1))

        echo "You must select number of k-points in each direction."

        echo "The following are the recommended number of k-points based on the POSCAR and the goal of L_i*n_k_i = ${stand_prod}:"

        echo "$ka $kb $kc"

        echo -n "Should we use these recommendations? (1/0) "   

        read  -n 1 UseRecKPOINTS ; echo ""

        UserInputHistory="${UserInputHistory}${UseRecKPOINTS}"

        if  [ "$UseRecKPOINTS" == 0 ]; then

                echo -n "Specify n_k_a: "

                read ka

                UserInputHistory="${UserInputHistory}${ka}\n"

                echo -n "Specify n_k_b: "

                read kb

                UserInputHistory="${UserInputHistory}${kb}\n"

                echo -n "Specify n_k_c: "

                read kc

                UserInputHistory="${UserInputHistory}${kc}\n"

                if ! [[ $ka =~ $any_int && $kb =~ $any_int && $kc =~ $any_int ]]; then

                        echo "I do not recognize your input as numbers. Script terminating."

                        exit 1

                fi

                FinalReminder="${FinalReminder}> You manually selected your number(s) of k-points so you may need to edit your lattice vectors.\nE.g. you may want to lengthen c if you have a slab and you chose a smaller than recommended n_k_c.\n"

        elif [ "$UseRecKPOINTS" != 1 ]; then

                echo $BadInput

                exit 1

        fi

        sed -i "s/KA/$ka/g" KPOINTS

        sed -i "s/KB/$kb/g" KPOINTS

        sed -i "s/KC/$kc/g" KPOINTS

fi

# submission.slurm section

if [ -f "submission.slurm" ]; then

        echo -n "Do you want to use the submission.slurm already in ${MyDir}? (1/0) "

        read  -n 1 UseThisSS ; echo ""

        UserInputHistory="${UserInputHistory}${UseThisSS}"

        if [ "$UseThisSS" == 1 ]; then

                MySS="submission.slurm"

        elif [ "$UseThisSS" != 0 ]; then

                echo $BadInput

                exit 1

        fi

else

        UseThisSS=0

fi

if [ "$UseThisSS" == 0 ]; then

        echo "Select a standard submission.slurm or non-standard submission.slurm format."

#       echo -n "(3:engineering_long / 2:engineering_q / 1:mendoza_q / 0:non-standard format) "

        echo -n "(2: general-long / 1:mendoza_q / 0:non-standard format) "

#       echo -n "(1:general-long / 0:non-standard format) "

        read  -n 1 UseSSFormat ; echo ""

        UserInputHistory="${UserInputHistory}${UseSSFormat}"

#        if [ "$UseSSFormat" == 3 ]; then

#                MySS="${StandardInputFileDirectory}/submission.slurm_engineering_long"

        if [ "$UseSSFormat" == 2 ]; then

                MySS="${StandardInputFileDirectory}/submission.slurm_general_long"

        elif [ "$UseSSFormat" == 1 ]; then

                MySS="${StandardInputFileDirectory}/submission.slurm_mendoza_q"

        elif  [ "$UseSSFormat" == 0 ]; then

                echo -n "Specify a path to a submission.slurm: "

                read -e MySS

                UserInputHistory="${UserInputHistory}${MySS}\n"

                if [ ! -f "$MySS" ]; then

                        echo "$MySS does not exist. Script terminating."

                        exit 1

                fi

        else

                echo $BadInput

                exit 1

        fi

        cp $MySS ./submission.slurm

fi

# The first line below should make the necessary replacement if using the standard submission file

# The following two will be necessary only if using a submission.slurm taken from elsewhere

sed -i "s/TITLE_HERE/${Title}/" submission.slurm

sed -i "s/^#SBATCH --job-name.*/#SBATCH --job-name ${Title}/" submission.slurm

sed -i "s/^export JOB=.*/export JOB=${Title}/" submission.slurm

echo "These are your submission.slurm settings:"

grep "#SBATCH -n " submission.slurm

grep "#SBATCH -N " submission.slurm

grep "#SBATCH --time" submission.slurm

echo -n "Should we use those settings? (1/0) "

read -n 1 UseSSsettings; echo ""

UserInputHistory="${UserInputHistory}${UseSSsettings}"

if [ "$UseSSsettings" == 0 ]; then

        echo -n "Specify n_cpus: "

        read n_cpus

        UserInputHistory="${UserInputHistory}${n_cpus}\n"

        if ! [[ $n_cpus =~ $any_int ]]; then

                echo "I do not recognize your input as a number. Script terminating."

                exit 1

        else

                read -r previous_n_cpus <<< $(echo `grep '#SBATCH -n' submission.slurm | grep -Eo '[0-9\.]+'`)

                sed -i "s/-n ${previous_n_cpus}/-n ${n_cpus}/g" submission.slurm

        fi

        echo -n "Specify N_nodes: "

        read N_nodes

        UserInputHistory="${UserInputHistory}${N_nodes}\n"

        if ! [[ $N_nodes =~ $any_int_range ]]; then

                echo "Removing the node constraint."

                sed -i "/#SBATCH -N/d" submission.slurm

        else

                read -r previous_N_nodes <<< $( grep '#SBATCH *-N' submission.slurm | grep -Eo '[0-9\.]+\-*[0-9\.]+' ) #echo `grep '#SBATCH -N' submission.slurm | grep -Eo '[0-9\.]+'`)

                sed -i "s/-N ${previous_N_nodes}/-N ${N_nodes}/g" submission.slurm

        fi

        echo -n "Specify time (n_days-n_hours): "

        read -n 1 n_days

        echo -n "-"

        read -n 2 n_hours

        echo ":00:00"

        UserInputHistory="${UserInputHistory}${n_days}${n_hours}"

        if ! [[ $n_days =~ $any_int_range ]] || ! [[ $n_hours =~ $any_int_range ]] ; then

                echo "I do not recognize your input as a number. Script terminating."

                exit 1

        else

                read -r previous_time <<< $(echo "$(grep '#SBATCH --time' submission.slurm )" )

                sed -i "s/^$previous_time/#SBATCH --time=${n_days}\-${n_hours}:00:00/g" submission.slurm

        fi

fi

echo -e $FinalReminder

echo -n "Do you want to submit the job? (1/0) "

read -n 1 SubmitJob ; echo ""

UserInputHistory="${UserInputHistory}${SubmitJob}"

echo $UserInputHistory > mkdirVASPuserInput

if [ "$SubmitJob" == 1 ]; then

        echo "Submitting $Title"

        sbatch submission.slurm

elif [ "$SubmitJob" != 0 ]; then

        echo $BadInput

        exit 1

fi

2. POTCAR_create

This script will generate a POTCAR file if given a list of elements to use

#!/bin/bash

MyDirectory="/mnt/home/djokicma/VASP/References/POTCARs"

MyCommand="cat "

MyAtoms=""

for atom in "$@"

do

        MyFile="$MyDirectory"/POTCAR_"$atom"

        if [ ! -f "$MyFile" ]; then

                echo cannot find $MyFile

                exit 1

        fi

        MyAtoms+="$atom"

        MyCommand+="$MyFile "

done

MyCommand+="> POTCAR_$MyAtoms"

echo "$MyCommand"

eval "$MyCommand"

echo "POTCAR_$MyAtoms successfully created" 

3. POTCAR_create_from_POSCAR

This script reads a POSCAR to automatically determine which elements to feed into script 2

#!/bin/bash

if [ "$1" != "" ]; then

    MyFile="${1}"

else

    MyFile="./POSCAR"

fi

# The command `sed "6q;d" file` will print the 6th line of file 

# The command `echo string | sed 's/ //g'` will return the string with no spaces

MyAtoms=`sed "6q;d" "$MyFile" | sed -z 's/\r//g;s/\n//g'`

MyAtomsNoSpace=`echo -n "$MyAtoms" | sed -z 's/ //g'`

echo Attempting to make POTCAR_"$MyAtomsNoSpace"

MyCommand="~/bin/POTCAR_create "

MyCommand+="${MyAtoms}"

eval "$MyCommand"

Electron Properties

To perform band structure calculations, there are several ways:

1. to extract the eigenvalues to plotting software (such as gnuplot),

2. to run p4vasp, or

3. to interface with Wannier90 and produce wannier projection.

Preparing the band structures are simple. First, take your output and run an SCF cycle. Then, take the CHGCAR (charge density file) and rerun the calculation with a NSCF run (by setting ICHARG to 11 in the INCAR). Also note, you must set ISMEAR = 0 if you have not already. Otherwise you get a weird and un-intuitive error. Applying symmetry may also cause issues. To be safe, set ISYM = 0 for the NSCF cycle.

You will also need to setup a k-point pathway in the KPOINTS file in order to calculate eigenvalues. Such a file will look as follows:

<Title and general info>

<number> ! number of k-points between each point specified

Line-mode !or 'line' tells VASP which setting to use

reciprocal !or 'cart'

<point 1>

.

.

.

<point n>

Analysis Script

So far this prints the final minimized energy from OUTCAR. I will update it with more functionality in the near future

#!/bin/bash

# My first script

if [ "$1" != "" ]; then

    MyFile=$1

else

    MyFile="OUTCAR"

fi

OptimizeBool=$(grep -n "reached required accuracy - stopping structural energy minimisation" $MyFile)

if [ "$OptimizeBool" == "" ]; then

    echo -e "Energy not minimized. \nFinal lines:"

    tail $MyFile

else

    echo -e "$(grep -A 2 -n "FREE ENERGIE OF THE ION-ELECTRON SYSTEM (eV)" $MyFile | tail -3)"

fi