Steps
GO for ini and fin structure
mind that IBRION = 2, and the atom index should be same.
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diff ini/POSCAR fin/POSCAR
relax INCAR
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Global Parameters
ISTART = 1 (Read existing wavefunction, if there)
ISPIN = 1 (Non-Spin polarised DFT)
LREAL = .FALSE. (Projection operators: automatic)
ENCUT = 600 (Cut-off energy for plane wave basis set, in eV)
LWAVE = .False. (Write WAVECAR or not)
LCHARG = .False. (Write CHGCAR or not)
ADDGRID= .TRUE. (Increase grid, helps GGA convergence)
Electronic Relaxation
ISMEAR = 0 (Gaussian smearing, metals:1)
SIGMA = 0.05 (Smearing value in eV, metals:0.2)
NELM = 90 (Max electronic SCF steps)
NELMIN = 6 (Min electronic SCF steps)
EDIFF = 1E-05 (SCF energy convergence, in eV)
NCORE = 4
Ionic Relaxation
NSW = 100 (Max ionic steps)
IBRION = 2 (Algorithm: 0-MD, 1-Quasi-New, 2-CG)
ISIF = 2 (Stress/relaxation: 2-Ions, 3-Shape/Ions/V, 4-Shape/Ions)
EDIFFG = -2E-02 (Ionic convergence, eV/AA)
# Add VDW
IVDW = 11
for graphite, set IVDW = 11 vaspkit -task 102 -kps G -kpr 0
Check the ini and fin structure
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perl ./dist.pl ./ini/POSCAR ./fin/POSCAR
the structure should less than 5 A
Interpolate images
using the nebmake.pl script.
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perl nebmake.pl ./ini/CONTCAR ./fin/CONTCAR 1
Prepare INCAR for Standard Relax
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ISTART = 0
ICHARG = 2
ENCUT = 600
PREC = Medium
ISIF = 2
LREAL = .FALSE.
ISMEAR = 0
SIGMA = 0.05
ISPIN = 2
NSW = 500
EDIFF = 1E-2
IBRION = 3
POTIM = 0
EDIFFG = -0.1
IOPT = 1
IVDW = 11
ICHAIN = 0
LCLIMB = .TRUE.
IMAGES = 3 # the number set in nebmake
SPRING = -5
Sub calculation
check the convergence with nebef.pl
Results
use nebresults.pl to get the result