CCL: CCL CCL: Negative frequencies with C1 symmetry (Orca)

[Grigoriy Zhurko <reg_zhurko=chemcraftprog.com>]

 Sent to CCL by: Grigoriy Zhurko [reg_zhurko**chemcraftprog.com]
 > I am not sure what you mean by „quackery“? Any optimiser
 brings the gradient to zero to find a stationary point. This stationary point
 can be a minimum, maximum or a n'th order saddle point. What kind of point was
 found is determined by analyzing the eigenvalue structure of the Hessian. It is
 not a bug or misbehaviour of the optimiser to land on a saddle point,
 especially, when you have loosely bound molecular complexes as is the case for
 explicit solvation. It is absolutely proper procedure to then search for a
 nearby minimum that eliminates the negative frequencies.
 > However, it is not the point to repeat the optimisation from
 "some“ other starting point and hope that it eliminates the negative
 frequencies.  Instead, what needs to be done is to displace the system along the
 normal mode with the (or one of the) negative frequency(ies) and then
 reoptimize.
   I tried this and it didn't help. My computation indeed finds a local minimun,
 not a saddle point.
   It is very strange for me to hear, that a saddle point can be found by the
 optimizer when the molecule has C1 symmetry. If that is possible, I suppose that
 the optimization convergence graph (energy vs optimization step) can show that.
 In my case, the optimization convergence graph shows that the energy is lowered
 during the optimization.
   Again, my main question is not how to get rid of the imaginary frequencies,
 but how to explain in the paper, why the computed energies are correct despite
 of these frequencies.
   Grigoriy.