Subject: MMOK : A summary...

From: Alexandre Hocquet <[email-masked]>
Date: Wed, 26 Mar 1997 17:16:07 +0400

Dear CCLers, 
Please find enclosed the summary of my question regarding the MOPAC keyword
MMOK.
Thanks to all that answered and especially to Thomas Strassner

Dear Alexandre,

for some information about the performance of that correction and about
ureas you could take a look at:

"A semiempirical AM1, MNDO and PM3 study of the rotational barriers of
various ureas, thioureas, amides and thioamides", M. Feigel, T. Strassner,
J. Mol. Structure, 283 (1993) 33.

Ab initio and molecular mechanics calculations of various substituted ureas
- rotational barriers and a new parametrization for ureas, T. Strassner, J.
Mol. Mod., 2 (1996) 217.

There was another publication dealing with peptide bond rotations and MOPAC,
where you might take a look on:

Ludwig, Schinke, Brandt, J.Mol.Mod. 1996, V2 N9 341-350

If you do have specific questions I will be happy to help you. You can email me
at [email-masked]

Best regards

Thomas Strassner

>Dear CCLers,
>
>As i am getting interested in ureas, i am more and more encountering the
>keyword MMOK
>in my literature searching. I understood that this is a MOPAC keyword (is
>it really ?)
>, that it is concerned with an amide structural correction for
>semiempirical methods,
>
>I dont know MOPAC, and the description of a similar keyword in the SPARTAN
>software
>(a molecular mechanics correction) is rather....rather spartan.
>
>Does someone know a reference (possibly other than the MOPAC manual) that
>describes
>the functionality of that strange keyword ? On what (published) structural
>results
>was it founded ?
>
>I will of course summarize the answers...
>
>Thanks in advance
>
>Alexandre Hocquet

************************************************************************
*****  Dr. Thomas Strassner                                        *****
*****  UCLA, Department of Chemistry and Biochemistry              *****
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************************************************************************
Alexandre Hocquet
Laboratorio de Cristalografia
Facultad de Ciencias Fisicas
Universidad de Chile
Blanco Encalada, 2008
Santiago Centro
Chile
fono : 56 2 678 45 19
fax : 56 2 696 73 59
email : [email-masked]