Low barriers from CI-NEB calculations

[Natalie Austin]

Hello,

I've been running CI-NEB calculations on CO2 dissociation on 55-atom NPs. I 
was able to get a converged NEB but the resulting barrier for dissociation 
was very small ~0.05 eV. I am a bit unsure about this result considering 
the TS energies I've come across for CO2 dissociation on transition metals 
are ~0.2 - 1 eV. My initial and final states were optimized using SCF 1E-8 
and forces 4E-5. When the NEB completed I found one single imaginary 
frequency, which appears to correspond to CO - O dissociation.  I was 
wondering if anyone has come across the issue where only small barriers 
were detected but not expected?

I've included the CI-NEB section in below. I've also attached my whole NEB 
input file and output and the resulting energy file and input file and 
molden file for the transition state. 
&MOTION
  &BAND
   NPROC_REP 20
   BAND_TYPE CI-NEB
   NUMBER_OF_REPLICA 8
   K_SPRING 0.01
    &OPTIMIZE_BAND
      OPT_TYPE DIIS
      OPTIMIZE_END_POINTS .FALSE.
      &DIIS
       MAX_STEPS 1000
       N_DIIS 7
      &END
    &END
    &REPLICA
     COORD_FILE_NAME 1.xyz
    &END REPLICA
    &REPLICA
    COORD_FILE_NAME 2.xyz
    &END REPLICA
    &REPLICA
     COORD_FILE_NAME 3.xyz
    &END REPLICA
    &REPLICA
    COORD_FILE_NAME 4.xyz
    &END REPLICA
    &REPLICA
     COORD_FILE_NAME 5.xyz
    &END REPLICA
    &REPLICA
    COORD_FILE_NAME 6.xyz
    &END REPLICA
    &REPLICA
     COORD_FILE_NAME 7.xyz
    &END REPLICA
    &REPLICA
    COORD_FILE_NAME 8.xyz
    &END REPLICA
   ALIGN_FRAMES .FALSE.
   ROTATE_FRAMES .FALSE.
  &CONVERGENCE_CONTROL
   MAX_DR    0.002
   MAX_FORCE 0.002  
   RMS_DR    0.001
   RMS_FORCE 0.001
  &END CONVERGENCE_CONTROL

Thanks, 

Natalie
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cu53zr2_long.inp
Type: chemical/x-gamess-input
Size: 3130 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cu53zr2_long.out
Type: application/octet-stream
Size: 4621371 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cu53zr2_long-1.ener
Type: application/octet-stream
Size: 10106 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment-0001.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cu53zr2_co2_pos_ts.inp
Type: chemical/x-gamess-input
Size: 2509 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment-0001.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cu53zr2_co2_vib-frequencies.mol-1.mol
Type: chemical/x-mdl-molfile
Size: 437512 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20160718/3ce2ea49/attachment.mol>