Committor, transition path ensemble

The path ensemble, as created by the transition path sampling methodology, is a statistically representative collection of trajectories leading from a reactant region to a product region. Further analysis of this ensemble of pathways is necessary to obtain rate constants, reaction mechanisms, reaction coordinates, transition state structures etc. In this section we will describe how to analyze the path ensemble by determining transition state ensembles, and how to test proposed reaction coordinates using committor distributions. 

Fig. 9. All configurations on transition pathways that have a committor of ps = 0.5 are members of the transition state ensemble. Each transition path contributes at least one configuration but possibly more to the transition state ensemble. The dashed line is the separatrix (or isocommittor 1/2 surface)...

Fig. 11. Representations of the folding event in 3 different order parameter planes. The free energy landscape from replica exchange is given by thin solid contour lines separated by 0.2 ksT. A few smoothed paths in the F-H ensemble are denoted by a scatter plot [small dots). Each dot represents a time slice along a path. Also given are the different committor ensembles pB < 0.2 light gray, 0.4 < pB < 0.6 in dark gray and pB > 0.9 in black. The apparent transition state saddle points in the FE landscape are indicated by arrows...

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