Re: Restarting namd-mopac QMMM

From: Marcelo C. R. Melo (
Date: Sat Feb 12 2022 - 15:47:44 CST

Hi Francesco,
Yes, NAMD will create the input files for MOPAC and, if you are using the
same qmBaseDir (or copying the contents of the previous run), MOPAC will
detect the temporary files from the previous run and use those as a
starting point for its SCF calculation. I thought ORCA (at least
until version 4.2) also did that automatically.
In any case, the *positions* are determined by NAMD, but the temporary
files from the previous MOPAC run are also used to accelerate the

On Sat, Feb 12, 2022 at 1:44 PM Francesco Pietra <>

> Hi Marcelo
> Does that mean that mopac continues automatically from its acquired
> positions? For orca doing that it must be forced to read previous .gbw and
> orbitals
> Thanks
> francesco
> On Sat, Feb 12, 2022, 6:47 PM Marcelo C. R. Melo <>
> wrote:
>> Hi Francesco,
>> If you are just continuing a QM/MM MD simulation, you do not need to
>> change the qmConfigLine. You can just ask NAMD for another 100000 steps
>> with the "run 100000" command.
>> All you need to do to continue the simulations is to set the initial
>> positions, velocities, and box dimensions using the restart files from your
>> previous simulations. For extending MD runs, the fact that this is a QM/MM
>> simulation does not change anything for NAMD.
>> Best,
>> Marcelo
>> On Sat, Feb 12, 2022 at 11:44 AM Francesco Pietra <>
>> wrote:
>>> Hi all
>>> I would like to use the keyword RESTART (of which I have no previous
>>> experience at all) to run in batches a very long QMMM with namd-mopac. If I
>>> understand, the keyword RESTART should be added to the qmConfigLine of the
>>> first completed run of, say,100000 steps.
>>> In order to continue the QMMM for further 100000 steps, what should the
>>> 'run' keyword indicate in config file of namd? 100000 or 200000?
>>> Thanks for advice
>>> francesco pietra

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