Re: [AMBER] errors in qm/mm

From: Gustavo Seabra <>
Date: Mon, 24 Nov 2014 09:43:18 -0300


Have you tried changing the defaul setting for DFTB_TELEC? It's not
something that should be messed with often, but may help in this situation.
You may try to set it to 100 just until yiu are over this problem, then
change it back to the default (0).

Hope that helps,
Gustavo Seabra.
Em 24/11/2014 03:11, "Ayesha Fatima" <> escreveu:

> Dear all,
> I am trying to run a qm/mm on a protein-ligand system. I have successfully
> done classical MD without errors. As per information on the mailing list,
> for qm/mm, i used a well equilibrated .rst file from the classical MM
> method and was able to do further equilibration with qm/mm using the PM3
> Hamiltonian. It is in the MD production phase.
> I want to repeat the same with SCC-DFTB but unfortunately it keeps giving
> errors in the equilibration phase such as
> QMMM SCC-DFTB: !!!! ============= WARNING ============= !!!!
> QMMM SCC-DFTB: Convergence could not be achieved in this step.
> QMMM SCC-DFTB: The calculation will continue, but energies and
> QMMM SCC-DFTB: forces for this step will not be accurate.
> I have looked around on the mailing list and know its a common error. I
> also tried using the PM3 equilibrated file and trying to further
> equilibrate it with the SCC-DFTB. But the error still remains. I am
> attaching my input file. I am sure someone has done it and resolved the
> issue. Could they share their experience?
> Thank you
> Regards
> Ayesha Fatima
> PhD candidate UM
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Received on Mon Nov 24 2014 - 05:00:02 PST
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