Re: [AMBER] errors in qm/mm

From: Marc van der Kamp <marcvanderkamp.gmail.com>
Date: Mon, 24 Nov 2014 08:03:32 +0000

Have you mentioned the amber/sander version you are using yet? An unpatched version 12 may cause problems.
Marc

Sent from my iPhone

> On 24 Nov 2014, at 07:02, Ayesha Fatima <ayeshafatima.69.gmail.com> wrote:
>
> Dear Dr. Andreas.
> The error is still there. Any other suggestion. thanks
>
>> On Mon, Nov 24, 2014 at 2:27 PM, Andreas Goetz <agoetz.sdsc.edu> wrote:
>>
>> Dear Ayesha,
>>
>> You are trying to converge the SCF very tightly. Probably your electron
>> density is well converged but not to the thresholds you requested. This
>> might be the reason for failure. Try setting tight_p_conv=0 (this is
>> default) and possibly scfconv=1.0e-8 which should be sufficient.
>>
>> I also noticed you are using a very large cutoff. Using cut=9.0 is usually
>> sufficient.
>>
>> All the best,
>> Andy
>>
>> --
>> Dr. Andreas W. Goetz
>> Assistant Project Scientist
>> San Diego Supercomputer Center
>> Tel : +1-858-822-4771
>> Email: agoetz.sdsc.edu
>> Web : www.awgoetz.de
>>
>>> On Nov 23, 2014, at 10:10 PM, Ayesha Fatima wrote:
>>>
>>> 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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>>
>>
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Received on Mon Nov 24 2014 - 01:00:03 PST
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