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Convergence problems with NEB calculations

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Kim Do Hwan

Thu Aug 04 2005, 04:24AM

Registered Member #351
Joined Thu Aug 04 2005, 04:02AM
posts 1

Hi,

I've been trying to perform VASP calculations for my system, especially organic molecules on semiconductor surface.
The calculations are O. K. in case of geometry optimization.
However, I can not find transition state with NEB method.
Each of the images do not converge even after 1000 runs.
I'm afraid I have used inapproprate variables in INCAR options, or that it may be difficult to find transition state for organic molecule on semiconductor system.

I used 3 or 5 images.

My settings for NEB calculations are

EDIFF = 1E-05 for electronic relaxation
ICHAIN = 0
EDIFFG = -0.1
IBRION = 3
POTIM = 0.05
SMASS = 2

Please inform me any method to solve the problems.

Thanks,
Kim, Do Hwan
[ Edited ]

admin

Fri Aug 05 2005, 10:36AM

posts 2329

for the VASP releases distributed by us, the INCAR tags to
do an NEB run are
IMAGES =
SPRING = -5

Brane

Wed Aug 10 2005, 12:24PM

Registered Member #83
Joined: Sat Feb 05 2005, 03:53AM
Location: U.S.
posts 14

I think he used the improved NEB program provided by Dr. Henkelman. In the improved NEB, ICHAIN=0 is for NEB, and SPRING=-5 is default. Maybe the small POTIM slows the convergence.
Try POTIM = 0.1 and remove SMASS parameter after some steps.

[ Edited Wed Aug 10 2005, 02:34PM ]

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