From NWChem
Viewed 2770 times, With a total of 4 Posts
|
|
|
Clicked A Few Times
Threads 3
Posts 6
|
|
| 11:24:38 AM PDT - Mon, Jun 3rd 2013 |
|
Hello Folks,
I am running into problems getting an IRC calculation to run and was hoping someone else might have some insight.
I am receiving an error that "The energy has increased" and the calculation dies before doing the first point of the MEP/IRC. I have tried decreasing the step size (stride) to no avail. I have tried tightening up the energy convergence criteria in the TS calculation. At this point I am considering tightening up the DFT grid size, but that has more ramifications since grids need to be consistent between calculations to compare energies.
Thanks for your help!
Input deck:
TITLE molecule
geometry noautosym
C -1.56583532 0.89980740 -0.46106375
C -0.63078461 1.82698720 -0.86157945
C -0.50773429 2.24918622 -2.30919751
H -1.44949302 2.07714793 -2.84402532
H 0.28275637 1.67258199 -2.80899191
H -0.24479137 3.30808189 -2.40178582
C -1.55906112 0.29368306 0.83927529
H -2.21346146 0.46986517 -1.22690280
S 0.57452173 2.28434060 0.27251061
C -0.11188030 -0.95552821 1.12771631
H -2.39624750 -0.36907737 1.06390518
H -1.28782623 0.97753389 1.66409184
S 1.38219886 -0.04057327 0.92765129
C -0.32367076 -2.07715447 0.09224193
C -0.39215468 -1.42587090 2.56874464
H -0.25842731 -0.61046728 3.28498429
H 0.29935385 -2.23912992 2.84821336
H -1.41677948 -1.81613178 2.66570304
H -0.15719796 -1.71031957 -0.92379821
H -1.34409850 -2.48456759 0.15829454
H 0.37792543 -2.90958221 0.27310725
end
basis spherical
C library 6-31G*
H library 6-31G*
S library 6-31G*
END
driver
maxiter 200
end
dft
xc b3lyp
iterations 2000
end
task dft freq
freq
reuse molecule.hess
end
mepgs
maxmep 300
maxiter 200
inhess 2
noxyz
evib 0.0005
stride 0.01
backward
mswg
end
task dft mepgs
Last few lines of output file:
----------------------------------------
| Time | 1-e(secs) | 2-e(secs) |
----------------------------------------
| CPU | 0.01 | 2.91 |
----------------------------------------
| WALL | 0.01 | 3.07 |
----------------------------------------
Expected decrease in energy 0.000500
Obtained decrease in energy -0.005967
-------------------------
The energy has increased
-------------------------
------------------------------------------------------------------------
dft mepgs failed 0
------------------------------------------------------------------------
This type of error is most commonly associated with calculations not reaching convergence criteria
------------------------------------------------------------------------
|
|
|
|
|
|
Gets Around
Threads 19
Posts 71
|
|
| 6:18:33 PM PDT - Sun, Aug 4th 2013 |
|
Your molecule.hess has imaginary frequency mode?
Try to set FORWARD direction.
|
|
Edited On 6:22:53 PM PDT - Sun, Aug 4th 2013 by Vladimir
|
|
|
|
|
|
Clicked A Few Times
Threads 3
Posts 6
|
|
| 12:08:55 PM PST - Tue, Feb 18th 2014 |
|
Hello Vladimir,
Here is the weird thing. The vibrational analysis says there is an imaginary mode (as you can see we run the frequency and pipe that into the IRC):
----------------------------------------------------------------------------
Normal Eigenvalue || Projected Infra Red Intensities
Mode [cm**-1] || [atomic units] [(debye/angs)**2] [(KM/mol)] [arbitrary]
------ ---------- || -------------- ----------------- ---------- -----------
1 -295.810 || 0.036177 0.835 35.267 20.733
2 -0.000 || 0.000044 0.001 0.043 0.025
3 -0.000 || 0.000015 0.000 0.014 0.009
4 -0.000 || 0.000013 0.000 0.012 0.007
5 0.000 || 0.000039 0.001 0.038 0.022
6 0.000 || 0.000037 0.001 0.036 0.021
7 0.000 || 0.000022 0.001 0.022 0.013
8 124.486 || 0.002547 0.059 2.483 1.460
9 146.712 || 0.000637 0.015 0.621 0.365
10 185.619 || 0.001857 0.043 1.810 1.064
11 207.290 || 0.000024 0.001 0.024 0.014
12 236.593 || 0.001386 0.032 1.351 0.795
13 273.500 || 0.003481 0.080 3.393 1.995
14 308.056 || 0.005062 0.117 4.935 2.901
As for setting it to forward direction, sometimes it gives me the same "energy increased" error, other times it works fine.
|
|
|
|
|
|
Gets Around
Threads 19
Posts 71
|
|
| 11:11:19 PM PDT - Fri, May 23rd 2014 |
|
Can anybody point me to the documentation about mepgs. I can't find any.
So
mswg - mass weight coordinstes
flip - ???
forward - forward irc direction
backward - backward irc direction
ircboth - ??? (both directions)
evib - Desired decrease in energy when following the imaginary normal mode away from a saddle point. (default=0.0001 Hartree) ???
stride - Determines how far apart points on the reaction path will be. STRIDE is used to calculate the step taken. (default = 0.1 sqrt(amu)*Bohr) ???
nircopt - number of optimization steps ???
maxmep - max optimization steps ???
nptopt - ???
eprec - ????
Sometimes I've got error:
norm not preserved
What's meaning of this error?
What's meaning of 2-nd geometry in *.bxyz and *.fxyz files? There is no corresponding energies in `grep \& *.nwo`.
1-st geometry is initial.
3-rd is a "point 0" of IRC
The answer can be given in the terms of http://www.cup.uni-muenchen.de/ch/compchem/geom/irc1.html
|
|
Edited On 1:47:50 AM PDT - Sat, May 24th 2014 by Vladimir
|
|
|
|
|
|
Gets Around
Threads 19
Posts 71
|
|
| 2:47:24 AM PDT - Sat, May 24th 2014 |
|
| evib = 0.0 is possible and 1st and 2nd geometry is equal in that case
|
|
|
AWC's:
2.5.10 MediaWiki - Stand Alone Forum Extension
Forum theme style by: AWC
