Prefactor

Changed in version 2.12: Fixed Hessian size validation bug where min2Freqs was never checked. Fixed float precision in QQ-HTST physical constants.

The prefactor job computes the harmonic transition state theory (hTST) rate prefactor using the Vineyard formula. This relates vibrational frequencies at a minimum and saddle point to determine the attempt frequency for a transition.

The prefactor job requires pre-computed minimum and saddle point structures. It uses the Hessian to obtain vibrational frequencies at each stationary point.

Usage

[Main]
job = prefactor

[Prefactor]
rate_estimation = htst
filter_scheme = fraction
filter_fraction = 0.9

The filter_scheme controls which frequencies contribute to the prefactor. Setting filter_fraction = 0.9 includes frequencies within 90% of the full range, filtering out very high-frequency modes that may be numerical artifacts.

Configuration

[Prefactor]