[AMBER] errors in qm/mm

From: Ayesha Fatima <ayeshafatima.69.gmail.com>
Date: Mon, 24 Nov 2014 14:10:57 +0800

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
Ayesha Fatima
PhD candidate UM

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Received on Sun Nov 23 2014 - 22:30:03 PST
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