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
------------------------------------------------------------------------
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