To add a further remark to Dave's comments:
ESP-derived atomic charges are dependent on the selection of points you
compute the ESP at, and thus they even depend on the orientation in
space of the molecule of interest, even for the same QM program and the
same QM method. This is a long-known issue in ESP-derived atomic charges.
This is the reason, why e.g. the RED server (F.-Y. Dupradeau) uses
standard orientations of the molecule of interest for the calculation of
RESP charges to allow for a better reproducibility here.
Best regards,
Anselm
On 11/27/2020 03:24 AM, David Cerutti wrote:
> The calculation of partial charges for optimal reproduction of the
> electrostatic potential around a molecule is only deterministic in the
> limit of an agreed upon figure of merit, a perfectly consistent method, and
> an identical data set. In your case, the data set is a series of
> points scattered around the molecule, as selected by either program, and
> the figure of merit is a least squares optimum given hyperbolic restraint
> equations. The two programs may not even perform that in precisely the
> same way, but I suspect that the root of your problem is the selection of
> the points at which to take the electrostatic potential for composing the
> fitting matrix. A better analysis is to take the partial charges coming
> from each program, select a set of your own points around the molecule
> where you think water or other matter might experience their electrostatic
> potential, and then calculate the charge models' projected electrostatics
> at those points. See how well those agree, and if the difference is still
> large then come back and we'll look at it some more.
>
> Dave
>
>
> On Thu, Nov 26, 2020 at 12:54 PM Michele Vanini <
> michele.vanini.student.kuleuven.be> wrote:
>
>> Dear all,
>>
>> I have a question regarding the partial charges calculation for a GAFF
>> parametrization.
>>
>>
>> I have calculated them with two methods
>>
>> GAUSSIAN+ resp (antechamber)
>>
>> GAMESS US + resp
>>
>>
>> Using the same molecule, the same level, HF 6-31G I obtain different
>> values.
>>
>>
>> Do you know how to fix this problem?
>>
>> If you prefer I can put all the input commands.
>>
>>
>> Regards
>> _______________________________________________
>> AMBER mailing list
>> AMBER.ambermd.org
>> http://lists.ambermd.org/mailman/listinfo/amber
>>
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Received on Fri Nov 27 2020 - 01:00:03 PST
