How to measure dihedral angle


I used the following to freeze a dihedral angle during optimization.
set optking {
frozen_dihedral = (" 1 6 7 8 ")

Is there a way to measure a dihedral angle using indices of four atoms? This is a sanity check to make sure the dihedrals were indeed frozen. The dihedral will be used for plotting against delta E.



I’m not aware that this is directly available at present in python - at least I can say that the optimization code does not presently make it available (I hope to fix this in the future). You could compute it from the geometry yourself.

However, you can find the value in the output file by looking (awk,grep,eyes,…) for “*D(1,6,7,8)”