Dear All,
We are trying to optimize geometries in the first excited state on ricc2 level (for a 24-atom system).
In planar arrangements there is no problem, but at several distorted geometries (a certain out-of-plane angle is always fixed at different values) we often encounter the following problem in the "optimization of ground-state cluster amplitudes" part:
'CC equations did not converge within 100 iterations'
(this occurs especially for big distortions, but not only)
We would appreciate any help on how to handle this problem.
For big distortions the ground and first excited states come very close to each other. We wondered if this could be the source of such convergence problems?
In such cases the ricc2 excitation energy was often negative (a couple of cycles before the convergence problem). Probably they are related to each other?
Thank you for the help in advance!
~András
