Pathways are calculated by starting a minimisation of some sort after stepping off the transition state specified in odata. Using MODE values of 1 and -1 will give the two sides of the path. With SEARCH 0 (or 3) or LBFGS minimisation the resulting pathway will only be an approximation to a true gradient line. For search type 6 (or 7) and RKMIN or BSMIN the results should be close to the true steepest-descent path. Note that gradient lines are properties of the potential energy surface alone, and do not depend upon masses. Mass weighting, or calculating pathways in the fictitious space with a kinetic metric, has now been implemented, but not in the BFGS minimisation or hybrid EF/BFGS routines.
From svn revision 24173 it is possible to follow a transition state search by a pathway calculation automatically. The transition state search can be specified by BFGSTS, including NOIT and NOHESS, or full eigenvector-following using SEARCH 2. The default minimisation uses eigenvector-following if no other method is specfied. Otherwise the paths can be calculated by specifying BFGSMIN, PMPATH, BBRSDM, RKMIN, or BSMIN. Example input and output can be found at http://www-wales.ch.cam.ac.uk/examples/OPTIM/. The following input is for a gradient-only hybrid eigenvector-following transition state search with pathways calculated using LBFGS energy minimisation:
|BFGSTS||100 3 25 0.001|
The DUPALLPATHS keyword results in a path.info file being created, which can be read into a discrete path sampling database for PATHSAMPLE using the ADDPATH keyword for that program.