Transition state

Observation | Parameter | TS OPTIMIZATION |
---|---|---|

Energy Change | TolE | 5.0000e-06 Eh |

Max. Gradient | TolMAXG | 3.0000e-04 Eh/bohr |

RMS Gradient | TolRMSG | 1.0000e-04 Eh/bohr |

Max. Displacement | TolMAXD | 4.0000e-03 bohr |

RMS Displacement | TolRMSD | 2.0000e-03 bohr |

In a TS optimization we are looking for a first order saddle point, and thus for a point on the PES where the curvature is negative in the direction of the TS mode (the TS mode is also called transition state vector, the only eigenvector of the Hessian at the TS geometry with a negative eigenvalue). As transition state finder we implemented the quasi-Newton like hessian mode following algorithm.This algorithm maximizes the energy with respect to one (usually the lowest) eigenmode and minimizes with respect to the remaining 3N - 7(6) eigenmodes of the Hessian.

`OptTS`

uses the eigenvector following algorithm to find the nearest stationary point on PES. This can be local minimum or transition state.

`PreOpt_Ends`

conflicts with `NEB_Restart_XYZFile`

.
You cannot use them at the same time.

`NEB-TS`

doesn't calculate the Hessian (Initial Hessian is stored in`orca_TSOpt.appr.hess`

, no idea where this if from)

zoomNEB is similar to AutoNEB to some extents. Both methods insert images around the saddle point region on the fly. But zoomNEB inserts several images as many as initial images once identifying the saddle point region, while AutoNEB insert images one by one until a maximal pre-defined number.