From NWChem
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1:40:53 AM PST  Fri, Mar 4th 2016 

Starting a neb calculation with TWO points ( start and end) is OK. However starting with TREE points gives an initial path with is wrong. Along the path the molecule collapses towards the geometric centre, this a the middle point, and start to expand towards a normal molecule but which is not the endpoint. I could verify that with the test in /nwchem6.6/QA/tests/ch4_zts. If you the test with the spline method this is ok, the same test with NEB is wrong.
 Now with a TS guess
geometry geometry nocenter
symmetry c1
C 0.000000 0.000000 0.000000
H 0.000000 0.000000 1.089000
H 1.026719 0.000000 0.363000
H 0.513360 0.889165 0.363000
H 0.513360 0.889165 0.363000
end
geometry endgeom nocenter
symmetry c1
C 0.000000 0.000000 0.000000
H 0.000000 0.000000 1.089000
H 1.026719 0.000000 0.363000
H 0.513360 0.889165 0.363000
H 0.513360 0.889165 0.363000
end
geometry midgeom nocenter
symmetry c1
C 0.000000 0.000000 0.000000
H 0.000000 1.000000 0.000000
H 1.026719 0.000000 0.000000
H 0.513360 0.889165 0.000000
H 0.513360 0.889165 0.000000
end
basis
* library STO3G
end
 print low
neb
print
kbeads 0.001
stepsize 0.2
nbeads 11
maxiter 2
hasmiddle
impose
end
task neb scf
Could you help?
thank you very much
jeanlouis




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7:43:37 AM PST  Mon, Jan 9th 2017 

Same problem on standard Nwchem on debain Jessie

Any news on this bug?




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4:31:05 AM PST  Mon, Feb 13th 2017 

Hi,
The very same thing happened to me (and this is related: [1] and [2]).
Two inputs using the very same options and geometries, one using NEB and the other using the ZTS method can be found here: [3]
The complete outputs and initial paths can also be found in the zip file.
Observe that NEB fails due to linear dependencies at some intermediate geometry, which is no surprise if you see the initial path: atoms eventually colapse to the origin.
ZTS method works fine.
Commenting the "hasmiddle" line produces the expected result from both methods.

Edited On 4:32:19 AM PST  Mon, Feb 13th 2017 by Dudektria



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