Ganesh,
> Thank you for your responses. I was hoping not to construct a new set of
> parameters for RDX and PETN. But I guess that is what is required.
Yes ;-)
> I am more worried about the bonded terms especially the dihedrals and their
> transferability.
I would be worried by (i) the vdW parameters of N & O in NO2 and model
of charges and then (ii) develop new dihedral FF parameters - Yes -
using Wolf2Pack.
R.E.D. Server Dev. proposes new charge models; for instance for the
OPLS force field where RESP 2.4 has to be used:
see
http://q4md-forcefieldtools.org/REDS-Development/popup/popkeyword.php
&
http://q4md-forcefieldtools.org/RED/resp/
> Francois, that article on nitroaromatics has various different charge
> schemes for different force fields. Some schemes seem unnecessary but I
> guess it was meant for comparison sakes.
oligo-nitro compounds -> like you; aromatic -> not like you
This paper shows you that GAFF associated with different model of
charges gives quite various results; the best results are obtained for
an unusual association...
regards, Francois
> On Tue, Feb 18, 2014 at 2:19 PM, FyD <fyd.q4md-forcefieldtools.org> wrote:
>
>> Dear Ganesh,
>>
>> Your molecules are quite particular:
>> Does GAFF handle these molecules & is the RESP model better than am1-bcc
>> here?
>> Better checking what is generated...
>> See for instance http://pubs.acs.org/doi/abs/10.1021/ct3011002
>> (although I do not understand the point in this article)
>>
>> R.E.D. Server provides three QM codes: GAMESS, Firefly & Gaussian...
>> Different versions of Gaussian are also provided at R.E.D. Server
>> Development
>>
>> If you use R.E.D. Server Development you can specify your own force
>> field atom types (in case of you want to create new one(s)) in the
>> Project.config file (MOLECULE1-ATMTYPE); You can also provide your own
>> frcmod (FF parameter) file as input (frcmod.user) in the input
>> archive...
>>
>> If you use R.E.D. Server Development you can specify the theory
>> model(s) (QM) used in geometry optimization (and MEP computation); see
>> the Configuration.py file...
>>
>> Concerning Pentaerythritol tetranitrate you might split this molecule
>> into two building blocks (although the molecule is quite small);
>> difficult to answer without looking at the optimized geometry(ies)...
>>
>> regards, Francois
>>
>>
>> > My apologies:
>> >
>> > 1) RDX cyclotrimethylenetrinitramine: These are nitramines and energetic
>> > materials. http://en.wikipedia.org/wiki/RDX
>> > 2) PETN Pentaerythritol tetranitrate
>> > http://en.wikipedia.org/wiki/Pentaerythritol_tetranitrate
>> >
>> > thanks,
>> > ganesh
>> >
>> > On Tue, Feb 18, 2014 at 8:30 AM, ABEL Stephane 175950
>> > <Stephane.ABEL.cea.fr>wrote:
>> >
>> >> Hello
>> >>
>> >> We don't know ... What are RDX and PETN?
>> >>
>> >> Stephane
>> >>
>> >> --------
>> >> Stéphane Abel, PhD
>> >> CEA Saclay DSV/IbItec-S/SB2SM & CNRS UMR 8221
>> >> Bat 528 Door 138C
>> >> Gif-sur-Yvette, F-91191 FRANCE
>> >> Phone (portable) : +33 6 49 37 70 60
>> >> ________________________________________
>> >> De : Ganesh Kamath [gkamath9173.gmail.com]
>> >> Envoyé : mardi 18 février 2014 15:23
>> >> À : AMBER Mailing List
>> >> Objet : [AMBER] Question about force field parameters for RDX and PETN
>> >>
>> >> Hi AMBER Folks,
>> >>
>> >> Is there a good set of parameters in GAFF for RDX and PETN. Could
>> someone
>> >> point it out to me please.
>> >>
>> >> I appreciate the time and help.
>> >>
>> >> Regards,
>> >> Ganesh
>>
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Received on Tue Feb 18 2014 - 23:00:02 PST
