Re: [AMBER] iron sulphur cluster parametrization

From: Francesco Oteri <francesco.oteri.gmail.com>
Date: Tue, 01 Nov 2011 12:46:51 +0100

Hi Ilyas,
Il 01/11/2011 12:25, Ilyas Yildirim ha scritto:
> Just a heads up - If you want to convert the CHARMM parameters to AMBER, there are
> slight differences between these two force fields (even though the functions
> representing the potential energy looks alike). If I am not mistaken, the E_vdw and
> E_dihedral terms are a little bit different.
I am reading on the net that there differences between the two ff but,
fortunately, the only problem is
related to unity conversion :)


>> Francesco,
>>
>>> So I guess I can use the avalaible CHARMM parameters.
>> I would test and demonstrate that these CHARMM parameters work in
>> association with the Amber FF you wish to use.
>>
>>>>> I've been running GAMESS-US, both as stand-alone and RED-server, but it
>>>>> fails to converge both with or without geometry optimization.
>>>> When? at the first optimization step?
>>> Yes, it stops at the first stage, but I guess the problem cames from
>>> bad charge-multiplicity couple I gave.
>> - If you provide a bad multiplicity value or a bad charge value the QC
>> code will crash reporting something like 'the number of electrons and
>> spin multiplicity provided are not compatible'
>>
>> - If you have a problem of SCF convergence this likely means that your
>> input structure is bad or that the wavefunction cannot be determined
>> for the spin multiplicity chosen.
>>
>>> I submitted a new run using Gaussian 2009 with the RESP-X1 (B3LYP/6-31*)
>>> charge model.
>>> I will report the outcome on the mailing list....
>> If you want to test another QM theory level, just ask us: we do want
>> to implement _user defined options_ in R.E.D. Server Development. We
>> can easily create a specific submission procedure to your problem.
>>
>> regards, Francois
>>
>>
>>
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>
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Received on Tue Nov 01 2011 - 05:00:08 PDT
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