Re: [AMBER] Total charge not zero

From: George Patargias <gpat.bioacademy.gr>
Date: Wed, 12 Feb 2014 16:33:00 +0200

Dear Francois,

Thanks for this feedback.

I will have a go with the RED server if I have time.

Best wishes
George

> Dear George,
>
>> I have created the parameters of a ligand with gaff setting the total
>> charge to 0 (which is the default). When I load the generated mol2 into
>> tleap and I issue
>>
>> charge lig
>> I get
>> Total unperturbed charge: -0.003001
>>
>> Is this a rounding issue or something?
>
> I would answer that a rounding off error at 10-3 should have the
> following shape:
> 0.000 +/-.00X
>
> a rounding off error at 10-4 should have the following shape:
> 0.0000 +/-.000X
>
> '3001' is strange - the answer is just I guess 'that is small'...
>
> If you use R;E.D. Server or better now R.E.D. Server Dev./R.E.D.
> Python there is not such an error; besides rounding off errors are
> strictly corrected in agreement with chemical equivalencing & the
> different charge constraints used during the charge fitting step.
>
> See http://q4md-forcefieldtools.org/REDS-Development/
> & Concerning rounding off errors:
> http://q4md-forcefieldtools.org/REDS-Development/Demo2-Files/Configuration.py
>
> # Correct charge value rounding off errors at an accuracy defined by the
> user
> # 6: correction at ?± 1.10-6 e
> # 5: correction at ?± 1.10-5 e
> # 4: correction at ?± 1.10-4 e
> # 3: correction at ?± 1.10-3 e (pay attention)
> # 2: correction at ?± 1.10-2 e (pay a lot of attention)
> # 1: correction at ?± 1.10-1 e (do not use)
> # 0: no correction is performed
> # The default of COR_CHR = 4
> COR_CHR = 4
>
> Just submit your PDB file at
> http://q4md-forcefieldtools.org/REDS-Development/ &
> http://q4md-forcefieldtools.org/REDS-Development/upload-log.php
> (without anything else; this is accepted by now) & compare...
>
> regards, Francois
>
>
>
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>


Dr. George Patargias
Postdoctoral Research Fellow
Biomedical Research Foundation
Academy of Athens
4, Soranou Ephessiou
115 27
Athens
Greece

Office: +302106597568


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Received on Wed Feb 12 2014 - 07:00:03 PST
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