I ran a Cl-NEB to find a TS. It converged but there is no imaginary vibrational mode for my "TS". How to solve this problem?
One more thing,shouldnt climbing NEB guarantee that the TS is a true tranistion state since it is pushing the highest energy image UPHILL until the forces are zero?
Thanks.
Cl-NEB problem
Moderator: moderators
Re: Cl-NEB problem
Yes, the climbing image should converge to a first order saddle.
There are some pathological cases (related to high symmetry critical points) where the NEB can pass through a higher order saddle. But these are rare cases and not to be generally concerned about.
Most likely, the problem is related to having good enough convergence of the saddle (to < 0.01 eV/Ang) or even more likely, that you have a converged dynamical matrix calculation. Make sure to have accurate forces, using ediff=1e-8 and check for convergence with displacements in the range of 0.001 to 0.01 Ang.
There are some pathological cases (related to high symmetry critical points) where the NEB can pass through a higher order saddle. But these are rare cases and not to be generally concerned about.
Most likely, the problem is related to having good enough convergence of the saddle (to < 0.01 eV/Ang) or even more likely, that you have a converged dynamical matrix calculation. Make sure to have accurate forces, using ediff=1e-8 and check for convergence with displacements in the range of 0.001 to 0.01 Ang.