Force convergence problem

Vasp transition state theory tools

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xi007
Posts: 9
Joined: Mon Jul 13, 2015 2:50 pm

Force convergence problem

Post by xi007 » Mon Nov 05, 2018 2:38 am

Dear Admin,

My CI-NEB calculations are not converging. I am trying to moving one H atom on the SiC surface into the subsurface. I used 7 images in the process and with one Gamma point calculation.The optimizer I used is IOPT=2. But after 1000 steps, the NEB is still not converged. It shows that the forces on each image is still very large, even more than 1 eV/A. Here is my INCAR:

general: geometry optimation-Calculation

Start Parameters for this run
ISTART = 0
ICHARG = 2
INIWAV = 1
PREC = Accurate
ISMEAR = 0
SIGMA = 0.05
ALGO = Fast
NSIM = 4
LPLANE = .TRUE.
NPAR = 4
ISYM = 0

Electronic minimisation
ENCUT = 500
NELM = 100
NELMIN = 4
LREAL = A
EDIFF = 1E-5
LWAVE = .FALSE.
LCHARG = .FALSE.

Ionic relaxation
ISIF = 2
NSW = 1000
EDIFFG = -0.01

ISPIN = 2
LVDW = .TRUE.

IBRION = 3
POTIM = 0
ICHAIN = 0
IMAGES = 7
SPRING = -5
LCLIMB = .TRUE.
IOPT = 2
-----------------------------------

I also tried to use IOPT=3, with TIMESTEP = 0.1, it is still not converged.

Thank you very much for your help!

xi007
Posts: 9
Joined: Mon Jul 13, 2015 2:50 pm

Re: Force convergence problem

Post by xi007 » Mon Nov 05, 2018 4:09 am

Here are my vaspgr files. Thank you very much in advance!
Attachments
vaspgr.tar.gz
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graeme
Site Admin
Posts: 1784
Joined: Tue Apr 26, 2005 4:25 am
Location: University of Texas at Austin
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Re: Force convergence problem

Post by graeme » Mon Nov 05, 2018 1:15 pm

I would need to see the calculation to understand the problem.

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