Re: QM/MM error in the charges

From: Josh Vermaas (joshua.vermaas_at_gmail.com)
Date: Fri Feb 28 2020 - 07:50:26 CST

I would recommend against editing the charges, since then you are no
longer using the force field as intended, and your methods section
becomes hard to write. Instead, I'd find a different partitioning
between QM and MM regions so that each region has integer charge. That's
what I meant by cutting somewhere else.

-Josh

On 2/28/20 7:44 AM, Aashish Bhatt wrote:
> Thank you sir for your response
>
> Can you please elaborate sir.
> I need to manually edit the charges or i am getting something wrong.
>
>
> Best Regards
>
> Aashish
>
>
> On Thu, Feb 27, 2020 at 8:31 PM Josh Vermaas <joshua.vermaas_at_gmail.com
> <mailto:joshua.vermaas_at_gmail.com>> wrote:
>
> Cut somewhere else between QM and MM regions. The errors are
> pretty clear, in that it demands integer charges so that PME
> works. Amber topologies do not have the "group" concept like
> CHARMM topologies do, so the atomic charges within a molecule
> likely don't add to an integer.
>
> -Josh
>
> On Thu, Feb 27, 2020 at 5:51 AM Aashish Bhatt
> <aashish.ph16221_at_inst.ac.in <mailto:aashish.ph16221_at_inst.ac.in>>
> wrote:
>
> Dear Sir/Ma'am
>
> I am trying to check bond breaking in my system with the help
> of QM/MM.
> I am getting the following error and i am using Amber topology.
> can you please look into it.
>
> *Info: 1) Group ID: 1 ; Group size: 9 atoms ; Total PSF
> charge: -0.412152
> FATAL ERROR: QM atoms do not add up to a whole charge, which
> is needed for PME.
> ------------- Processor 0 Exiting: Called CmiAbort ------------
> Reason: FATAL ERROR: QM atoms do not add up to a whole charge,
> which is needed for PME.*
> *
> *
> Best Regards
>
> Aashish
>

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