<div dir="ltr"> Hi Natalie,<div><br></div><div>apparently the TS is already at the second bead of the NEB, very close to the initial state (the RMSD is the smallest 0.307756). </div><div>This is unusual. Are you sure that the initial state is optimised? What happens if you allow the optimisation of the end points during the NEB?</div><div><br></div><div>Regards</div><div>Marcella</div><div><br></div><div><br><br>On Monday, July 18, 2016 at 4:22:09 PM UTC+2, Natalie Austin wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Hello,<br><br>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?<br><br>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. <br>&MOTION<br>  &BAND<br>   NPROC_REP 20<br>   BAND_TYPE CI-NEB<br>   NUMBER_OF_REPLICA 8<br>   K_SPRING 0.01<br>    &OPTIMIZE_BAND<br>      OPT_TYPE DIIS<br>      OPTIMIZE_END_POINTS .FALSE.<br>      &DIIS<br>       MAX_STEPS 1000<br>       N_DIIS 7<br>      &END<br>    &END<br>    &REPLICA<br>     COORD_FILE_NAME <a href="http://1.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F1.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNH7Iopg33wy6-CUZSLr3wQXvVUl3Q';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F1.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNH7Iopg33wy6-CUZSLr3wQXvVUl3Q';return true;">1.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>    COORD_FILE_NAME <a href="http://2.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F2.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEg9F2aOHK3tMd1YdM1qZ9TAlxDZA';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F2.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEg9F2aOHK3tMd1YdM1qZ9TAlxDZA';return true;">2.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>     COORD_FILE_NAME <a href="http://3.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F3.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNH1BDabusB07E5oAZHboYi_Joc-Qw';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F3.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNH1BDabusB07E5oAZHboYi_Joc-Qw';return true;">3.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>    COORD_FILE_NAME <a href="http://4.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F4.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNHYalszAREV_qWgDaHDUqgHkDRdIQ';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F4.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNHYalszAREV_qWgDaHDUqgHkDRdIQ';return true;">4.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>     COORD_FILE_NAME <a href="http://5.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F5.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNE5QB9Ca-BJ6v-OoXrAE2N_5bWw_A';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F5.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNE5QB9Ca-BJ6v-OoXrAE2N_5bWw_A';return true;">5.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>    COORD_FILE_NAME <a href="http://6.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F6.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFKiaKXfnHcDtPvBngB_4YiE1oeqA';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F6.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFKiaKXfnHcDtPvBngB_4YiE1oeqA';return true;">6.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>     COORD_FILE_NAME <a href="http://7.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F7.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNECqkY4FwcRIE9PK_Wkg3zUzZ8fbQ';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F7.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNECqkY4FwcRIE9PK_Wkg3zUzZ8fbQ';return true;">7.xyz</a><br>    &END REPLICA<br>    &REPLICA<br>    COORD_FILE_NAME <a href="http://8.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F8.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEO9aojt2ZtiGdtY7hOpXzs2LjYmw';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2F8.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNEO9aojt2ZtiGdtY7hOpXzs2LjYmw';return true;">8.xyz</a><br>    &END REPLICA<br>   ALIGN_FRAMES .FALSE.<br>   ROTATE_FRAMES .FALSE.<br>  &CONVERGENCE_CONTROL<br>   MAX_DR    0.002<br>   MAX_FORCE 0.002  <br>   RMS_DR    0.001<br>   RMS_FORCE 0.001<br>  &END CONVERGENCE_CONTROL<br><br>Thanks, <br><br>Natalie<br></div></blockquote></div></div>