Re: MOPAC Point Charges

From: Marcelo C. R. Melo (
Date: Mon Aug 20 2018 - 16:40:46 CDT

Hello again,
Actually, MOPAC does support electrostatic embedding (make sure you have
the "QMMM" keyword in your MOPAC configuration line), but it does not take
the positions and charges of the classical atoms around the QM atoms, it
actually takes a file with the electrostatic potential at the position of
each QM atom (that is why the file is so much smaller).
Take a look at the documentation <> (

Marcelo Cardoso dos Reis Melo
PhD Candidate
Luthey-Schulten Group
University of Illinois at Urbana-Champaign
+1 (217) 244-5983
On Mon, 20 Aug 2018 at 13:31, Gerard Rowe <> wrote:
> Hi,
> I'm getting my feet wet running some QM/MM calculations, and I noticed a
> difference between how MOPAC and Orca calculations are set up. When I run
> with Orca, a sizeable point charge file is created and read by the
> program.  However, I can't find point charge information anywhere in the
> working folder for MOPAC calculations.  Is this because MOPAC doesn't have
> support for point charges?  Or is there possibly a keyword that I'm missing
> in the input?
> Thanks,
> Gerard

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