On Tue, Jun 04, 2019, Anthony Bogetti wrote:
>
>I'm looking to set up a simulation system that contains two charged
>molecules separated by some distance (20 Angstroms).
> I believe it has something to do with the charge separation.
>I am able to perform single point energy calculations on these systems just
>fine in Orca (I tried it just to see).
Does the Orca calculation have the same solvent molecules as the Amber
QM/MM? Have you compared orca to sqm with the same input geometry to
see if Amber/sqm is failing to converge systems (especially pure QM
systems) that orca is OK with? (That, of course, would not be
surprising, since Amber's SCF convergence options are limited.)
Also, SCC-DFTB treats self-consistency in a unique fashion. Might be
worth a quick test to see if you have the same problem with something
like PM6.
....dac
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Received on Fri Jun 07 2019 - 11:30:03 PDT
