Error in running MEPGS calculation


Click here for full thread
Clicked A Few Times
Hello,

I am trying to run MEP calculation on a simple ethylene oxide molecule. 
I tried running it in Forward, Backward as well as default (both) directions
So i start the job from coordinates of optimized TS structure with negative imaginary frequencies and then run MEPGS
For Forward as well default calculations, the GS OPT starts (step0) but after 200 iterations fails to converge...which should be the starting structure (TS already optimized)
For the backward calculation the energy increases and gives me an energy convergence failure...
Since I have ran the same molecule with another software (so I know the IRC works)....I am not sure what part is not working ....please explain and suggest changes


Here is the input
start TS_Eth_h2o2_B3LYP_IRCb

  1. geo from M06-L

geometry units angstroms
C     0.70240430     1.02854192     0.01900758
C -0.42716827 1.85861995 0.04102502
H 1.29500754 0.97410043 -0.89356705
H 1.30159049 0.91820617 0.92428135
H -0.92398310 2.14543825 -0.88229354
H -0.91822796 2.11267884 0.97925056
O -0.00444306 -2.26509742 0.06769202
H -0.23814281 -2.41577937 -0.85742490
H -0.58224747 -0.47936882 0.76067322
O -0.16938925 -0.35319650 -0.10605228
end

basis
  • library aug-cc-pvdz
end

Driver
Maxiter 100
end

dft
XC B3LYP
Maxiter 100
grid xfine
end

task dft Freq

freq
reuse TS_Eth_h2o2_B3LYP_IRCb.hess
end

mepgs
maxmep 300
maxiter 200
inhess 2
noxyz
evib 0.0005
stride 0.01
Backward
mswg
end

task dft mepgs


error from forward and default calculations:
---------------------------------------------------------------
Failed to converge in maximum number of steps or available time
---------------------------------------------------------------


 Step       Energy      Delta E   Gmax     Grms     Xrms     Xmax   Walltime
---- ---------------- -------- -------- -------- -------- -------- --------
@ 200 -230.12944427 3.8D-12 0.00053 0.00018 0.00000 0.00000 20803.0
                                             ok       ok       ok

..................



------------------------------------------------------------------------
mepgs: gsopt failed 0
------------------------------------------------------------------------
There is an error related to the specified geometry
------------------------------------------------------------------------

Error from backward calculation:

         Expected decrease in energy              0.000500

         Obtained decrease in energy             -0.000533

-------------------------
The energy has increased
-------------------------
------------------------------------------------------------------------
dft mepgs failed 0
------------------------------------------------------------------------
This type of error is most commonly associated with calculations not reaching convergence criteria


All the help is greatly appreciated

Thanks,
Pansy