Dear Kamali,
IOp(6/33=2) corresponds to the default algo. of the Kollman's group.
iop(6/33=2,6/41=10,6/42=17) does not correspond to the default algo...
-> I think you should read to understand what these IOP means.
http://www.gaussian.com/g_tech/g_ur/k_iop.htm
http://www.gaussian.com/g_tech/g_iops/ov6.htm
IOp(6/33=2) is not documented; it pnly means 'print the MEP'...
Reliable calculations with Antechamber?
Do not ask me - I do not use/support Antechamber.
You might also be interested in reading the R.E.D. article:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2918240/
Problems (orientation & conformation, algo in MEP computation,
chemical equivalencing and charge fitting, etc...) related to MEP
computation are described; I hope this describe why R.E.D. was
developed...
regards, Francois
> I've decided to just use the Antechamber method for now, because I'm more
> familiar with it. Initially, what I had done is submit output from Ante_RED
> to Gaussian. I only had a Link 0 header like this:
>
> *%Mem=4096MB*
> *%NProc=8*
> *
> *
> *#P HF/6-31G* SCF=(Conver=6) NoSymm Test*
> * Pop=mk IOp(6/33=2) GFInput GFPrint*
> *
> *
> *MEP - Input generated by R.E.D.-IV MOLECULE*
>
> while changing the basis set and level of theory. Typically, for
> antechamber, my input for the Gaussian has Link0 and Link1 before and after
> the molecular structures:
>
> *%NProc=8*
> *%mem=4096MB*
> *%chk=sa_charged_gauss101.chk*
> *#p opt freq HF/6-31G* formcheck*
> *
> *
> *Title Card Required*
> *
> *
> *--- molecular structure ---*
> *
> *
> *--Link1--*
> *%chk=sa_charged_gauss101.chk*
> *%mem=4096MB*
> *%NProc=8*
> *#p HF/6-31G* geom=allcheck guess=read pop=mk iop(6/33=2,6/41=10,6/42=17)*
>
> Could I submit the first through antechamber and still have reliable
> calculations? I know that the grid information is missing in the first
> Link0 section I sent you.
> On Sun, Jul 7, 2013 at 12:03 PM, FyD <fyd.q4md-forcefieldtools.org> wrote:
>
>> Dear Kamali,
>>
>> > Thank you so much for your detailed reply. I have one follow-up question
>> > for you: Do you know if it is possible to use Antechamber to generate
>> RESP
>> > charges using a level of theory other than HF/6-31G*?
>>
>> I would answer try and see ;-) Antechamber (and R.E.D.) just take the
>> MEP computed by QM and perform charge fitting whatever is the QM
>> theory level...
>>
>> You could also download R.E.D. III.x; modify the source code so that
>> the 'RESP-A1' charge model use the QM theory level of your choice...
>>
>> regards Francois
>>
>> PS If you need it we can modify the source of R.E.D. for you...
>>
>>
>> > On Thu, Jul 4, 2013 at 10:51 AM, FyD <fyd.q4md-forcefieldtools.org>
>> wrote:
>> >
>> >> Dear Kamali,
>> >>
>> >> > I actually do have another question. I would like to generate charges
>> >> using
>> >> > a basis set besides HF/6-31G* and AM1-BCC, and I was wondering if (a)
>> the
>> >> > RED Server has or will have such a potential, and (b) if you have any
>> >> > suggestions about generating charges with other, non-standard basis
>> sets.
>> >>
>> >> The use of HF/6-31G* is related to implicit polarization requested in
>> >> the additive Amber force field model. See
>> >> http://ambermd.org/doc6/html/AMBER-sh-19.4.html#sh-19.4
>> >> Be aware of what you do when using MP2 or DFT methods. For instance
>> >> MP2/aug-cc-pTVZ is used in the non-additive/polarizable FF model.
>> >>
>> >> Concerning AM1-BCC, the later approach is supposed to be an
>> >> 'approximation/simplification' of the RESP approach. Considering that
>> >> HF/6-31G* cost nothing (from a cpu point of view) our days I do not
>> >> understand why one would need an 'approximation' of the RESP method...
>> >> and obviously approximation/simplification has nothing to do with
>> >> breaking chemical equivalencing (just my personal opinion)...
>> >>
>> >> R.E.D. Server charge models are described at:
>> >> http://q4md-forcefieldtools.org/REDS/popup/popkeyword.php
>> >> R.E.D. Server Development charge models are described at:
>> >> http://q4md-forcefieldtools.org/REDS-Development/popup/popkeyword.php
>> >>
>> >> regards, Francois
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Received on Wed Jul 10 2013 - 01:30:03 PDT
