Re: QM/MM With Mopac Error

From: Marcelo C. R. Melo (
Date: Fri Sep 15 2017 - 07:36:26 CDT

Hello again,
Without a closer look at your output files this may be hard to asses.
You should verify NAMD's log file and make sure that the qmBaseDir and
qmParamPDB match the files you are inspecting. Sometimes, just cleaning
your qmBaseDir may help to make sure you are inspecting newly created files
and not leftover files from previous successful simulations. My first
suspicion is regarding files and configuration mistakes because this tipe
of error is very unlikely to happen. Even with bad geometries, MOPAC would
still return the correct number of charges.
That said, MOPAC's keyword"GEO-OK" will speed up the calculation by
removing "safety" checks that could identify problems with your geometry,
and should only be used in a very stable system. Try running without that
keyword and let me know how that works.

Marcelo Cardoso dos Reis Melo
PhD Candidate
Luthey-Schulten Group
University of Illinois at Urbana-Champaign
+1 (217) 244-5983
On 13 September 2017 at 15:27, Nisler, Collin R. <> wrote:
> Hello, I'm back with another QM/MM question. I am attempting to run QM/MM
> with mopac2016. I followed the instructions for installation and all seems
> to have gone well. When I attempt to run the simulation, I get the error "FATAL
> ERROR: Error reading QM forces file. Wrong number of atom charges". I
> checked the output of mopac in the BaseDir (the qmmm_0.input.out file) and
> as far as I can tell everything went fine as it finished successfully. I
> have tried to run this with multiple different selections for the QM
> region, including one that was just a single residue. This is the QM input
> section of the NAMD conf file:
> qmForces on
> qmParamPDB MmC23_ASI_QM.pdb
> qmColumn beta
> qmBondColumn occ
> QMElecEmbed on
> QMSwitching on
> qmBaseDir /mnt/home/nisler.1/labhome1/NAMD/QMMM/MmC23P15/QMMM/mop-
> mineq-01/QMmopMin01
> qmMult 1 1
> qmSoftware mopac
> qmExecPath /export/labhome1/nisler.1/opt/mopac/MOPAC2016.exe
> QMOutStride 1
> QMPositionOutStride 1
> Something must be happening during the mopac simulation that is changing
> the charges in the file being input to NAMD, but I'm not certain. Any help
> would be greatly appreciated, thanks.
> Collin Nisler

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