[Pw_forum] What to do when NEB calculation is difficult to converge?
Xunlei Ding
ding at sissa.it
Sun Aug 27 09:39:26 CEST 2006
Dear all,
I am now doing a neb calculation on a surface adsorption system with
pwscf3.0
The default values are used in the calculation as below:
calculation = neb
restart_mode = restart
opt_scheme = quick-min
num_of_images = 7
nstep = 500
first_last_opt = F
coarse-grained phase-space = F
use_freezing = F
ds = 1.0000 a.u.
CI_scheme = highest-TS
k_max = 0.6169 a.u.
k_min = 0.6169 a.u.
path_thr = 0.1000 eV / A
initial path length = 12.2601 bohr
initial inter-image distance = 2.0434 bohr
It has more than 400 iterations and has not converged. Should I change
some settings, such as ds, or k_max and k_min?
Below are the activation energies for the last few iterations, and they
are not monotone decreasing but oscillating.
Would anybody give me some suggestions?
activation energy (->) = 0.273443 eV
activation energy (->) = 0.273431 eV
activation energy (->) = 0.273719 eV
activation energy (->) = 0.273765 eV
activation energy (->) = 0.273207 eV
activation energy (->) = 0.273148 eV
activation energy (->) = 0.273311 eV
activation energy (->) = 0.273501 eV
activation energy (->) = 0.272957 eV
activation energy (->) = 0.272818 eV
activation energy (->) = 0.272865 eV
activation energy (->) = 0.273155 eV
activation energy (->) = 0.272750 eV
activation energy (->) = 0.272463 eV
activation energy (->) = 0.272443 eV
activation energy (->) = 0.272777 eV
activation energy (->) = 0.272574 eV
activation energy (->) = 0.272118 eV
activation energy (->) = 0.272080 eV
activation energy (->) = 0.272367 eV
activation energy (->) = 0.273228 eV
activation energy (->) = 0.272663 eV
activation energy (->) = 0.272621 eV
activation energy (->) = 0.272935 eV
activation energy (->) = 0.273033 eV
activation energy (->) = 0.272427 eV
activation energy (->) = 0.272386 eV
activation energy (->) = 0.272558 eV
activation energy (->) = 0.272823 eV
activation energy (->) = 0.272391 eV
Yours,
Ding
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