From: Gumbart, JC (gumbart_at_physics.gatech.edu)
Date: Thu Jul 25 2024 - 12:46:36 CDT

This is a good question. I wasn’t involved in the addition of support for ORCA, so I can’t comment on the logic behind it. I suspect it would be fine to remove the opt keyword and instead just make sure to use the optimized geometry as input.

Best,
JC

On Jul 23, 2024, at 4:29 PM, Vardan Vardanyan <vv25_at_rice.edu> wrote:

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Dear Comunity

I am using fftk to define the parameters of my ligands (they are big cyanin dyes, and I am using the framgmetion technique).

For the quantum calculations, I chose ORCA. In step 4, for bond and angle optimization, where I have to reconstruct the potential energy surface, the fftk writes hess.inp file.
It gives the error:

    ----------------------------------------------------------------------------
                                   ERROR !!!
       The optimization did not converge but reached the maximum
       number of optimization cycles.
       As a subsequent Frequencies calculation has been requested
       ORCA will abort at this point of the run.
       Please restart the calculation with the lowest energy geometry and/or
       a larger maxiter for the geometry optimization.
    ----------------------------------------------------------------------------

I changed the theory level and basis set, but nothing helped. I also increased the maxiter for the geometry optimization.

So I have two questions:

First, why do we need geometry optimization at this stage if we have already done it in the beginning (according to the tutorial)? Why can't we import coordinates from the initial structure obtained by geometry optimization ( at the MP2 level)?

Second, how to resolve the error from Hess.inp.

Thanks,
VV.