On Wed, May 12, 2010 at 3:12 AM, Hoshin Amber <85hskim.gmail.com> wrote:
> Dear, Amber user
>
> I'm trying to do dynamics of sugar(glucose, fructose, sucrose) solvation in
> ionic liquids.
> Before using ionic liquids structure to make solvent box, I ran
> antechamber(Am1-bcc).
> But some papers regarding my experiment have used gaussian03 for optimizing
> their structure and then use antechamber(RESP, or ESP).
>
> Nevertheless I used same molecule(same structure), the charge value using
> AM1BCC is different from using Gaussian-RESP(or ESP)
> (For example, N2 on the imidazolium ring using AM1BCC and RESP
> respectively,
> : -0.017 / 0.19)
>
> Why there are great difference between AM1BCC and RESP? Which one is
> precise
> value of charge? Using AM1BCC directly. Or using Gaussian-ESP?
>
> (P.S Ionic liquids are the liquid that are composed of only ion pair. They
> are not standard solvent in AMBER force field. One of ionic liquids which
> I'm trying to use is EmimTfO(1-ethyl-3methylimidazolium
> Trifluoromethylsulfonate) In case of Emim TfO, Emim is cation(+1), and TfO
> is anion(-1))
>
I would use the Gaussian RESP if you've already done that calculation, as
that's how the rest of the amber charges are derived (RESP/HF 6-31G*).
AM1BCC should be sufficient for many applications, but I'd say RESP would be
the better option to use. They shouldn't differ too much though...
However, if I had both I'd use RESP (assuming it was done properly).
Others may chime in with their comments and/or more professional opinions.
All the best,
Jason
> Finally, I'm the beginner of Amber and Molecular Dynamics. Explain in
> detail
> please.
>
> Thank you for your help in advance.
>
> Regards,
>
> Hoshin Kim
>
>
>
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--
Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Graduate Student
352-392-4032
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Received on Tue May 11 2010 - 14:00:07 PDT
