Debugging odd transition states in OPTIM

Sometimes in OPTIM high energy transition states will be encountered. There are several strategies for understand why these are occurring.

1. OPTIM and PATHSAMPLE may be able to fine lower energy connections if the calculations are allowed to continue. This can very inefficient. One way of preventing high energy transition states from occurring is to explicitly prevent transition states of a certain energy or above from being allowed. This is done by using the keyword MAXTSENERGY in both PATHSAMPLE and OPTIM.

2. If letting the calculation resolve the problem or MAXTSENERGY does not work looking at the interpolation is necessary. In order to do so, new OPTIM keywords, DEBUG, DUMPNEBEOS, and DUMPNEBXYZ need to be added to print the NEB interpolated energy and coordinates in the files neb.xyz.31267.<n>, and neb.EofS.<n>.31267.

DEBUG 
DUMPNEBEOS 100
DUMPNEBXYZ 100

3. Another strategy is to use BHINTERP to use basin-hopping to generate more physically reasonable interpolations between the end points. To do so you to use the keywords BHINTERP and BHDEBUG in OPTIM.

BHDEBUG
BHINTERP 10.0 -350.0 100 0.001 5.0 0.4 0.5 0.05 0.8

--mp466 13:48, 23 June 2009 (BST)