Subject: MM3-summary

From: <[email-masked]>
Date: Thu, 21 Mar 96 11:26:04 +0100

Dear members of CCL!

Best greetings to all those who answered my request:

I need MM3 parameters (stretching constants, torsional constants,
bending parameters, etc.) for bonds containing Si,C,H,X (X=F,Cl,Br,I)
(atoms arranged in all possible variations). Can you tell me, where I can
find these parameters (literature, or another existing force field 
program already providing such parameters)? All replies are highly
acknowledged!
Best wishes to everyone

Doz.Dr.K. Hassler
Institut fuer Anorganische Chemie, Technische Universitaet Graz,
Stremayrgasse 16
present e-mail: [email-masked]

Here are the answers!

1) Dipl.Ing. Zuegg (Institute of Organic Chemistry, University of 
Technology Graz, Stremayrgasse 16) wrote, that one can find some
useful literature about SiC SiO SiCl SiS MM2 parameters in
Review of Computational chemistry Vol. 6.

2)
From:	FULTRX::"[email-masked]" 12-MAR-1996 10:25:09.56
        Dear Dr. Hassler,

        The basis for the "parameter estimator" in MM3(94) was published a
while ago, "Allinger et al., J.Mol.Struct. (THEOCHEM) 312 (1994) 69-83".
In there, you can find methods for generating parameters for the entire
periodic table.  You should be aware that such parameters are prone to
errors, but they will let you start calculations while you are hunting for
more accurate values.  I've had fairly good experience with them so far.

        Best Regards,

        Per-Ola Norrby

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 *  Per-Ola Norrby
 *  The Royal Danish School of Pharmacy, Dept. of Med. Chem.
 *  Universitetsparken 2, DK 2100 Copenhagen, Denmark
 *  tel. +45-35376777-506, +45-35370850    fax +45-35372209
 *  Internet: [email-masked], http://compchem.dfh.dk/

3)
From:	SMTP%"[email-masked]" 12-MAR-1996 15:58:19.15

Hellow, Dr. Hassler
As you may know, C, H, and Si are fundamental elements for constructing
force field.  Therefore, they belong to primary ones to be parameterized.
For MM3 parameters, you can find from literatures or MM3 program manual.
You may ask directly Professor Allinger's group.  Here is their WWW address;
http://europa.chem.uga.edu.
For MM3 halogen parameters, Cl and I are parameterized, and F is almost ready,
and Br is not ready, I think.
I guess it will take a while to complete the MM3 halogen parameters.
I am the guy who parametrized MM3 monochloroalakanes.  This work has just been
done, and submitted for publication.
Let me know if you need further information.
Good Bye!

Sincerely,
JY Shim

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4)
From:	FULTRX::"[email-masked]" 12-MAR-1996 16:20:27.99

Appendix 1 in Reviews in Computational Chemistry, Volume 7, VCH Publishers,
 1995 is called "Published Force Field Parameters" and it may contain what 
you need.
_______________________________________________________________________________

5)
From:	FULTRX::"[email-masked]" 12-MAR-1996 21:13:34.05

Dear Dr. Hassler,

I do not have my bibliography on these items with me curretnly, but I can 
tell you if you look at the papers published in JOC, JCompChem, JMolStruct 
and Tetrahedron by my co-workers S.G. Cho, R. J. Unwalla, F. K. Cartledge 
and I, you will find a good starting place for the MM2 values which can 
accurately supplement or replace those in the public domain versions of 
MM2. We published all parameters to be used with MM2.

I was s student of Allinger who worked on MM1 and MM2 with him, thus I 
understand the process better than most. You will also see that we used 
good ab initio data to help develop parameters where exp data was missing. 
Also recognize that this data was generated 10 years ago, when widespread 
use of full geometry optimization was rare!

I cannot vouch for the accuracy of any MM3 parameters for silicon systems, 
as I have not worked in that area, nor have I funded Prof. Allinger to do 
so. I would be very careful with use of MM3 in that context.

Let me know if I can be of further assistance.

    ++++++De mortuis nil nisi bonum.++++++++++*
    Dr. Salvatore Profeta, Jr.
    Computational Polymorphism, Ltd.
    104 Cottage Lane
    Durham,  NC 27713-9387
    (919) 544-2299/5304 (Fax)
    email: [email-masked] (neutral zone)
    email: [email-masked] (courtesy acct)
    ++++++Sic transit gloria mundi++++++++++++

6)
From:	FULTRX::"[email-masked]" 13-MAR-1996 22:42:11.28

Hi, Dr. Hassler.

I don't know of any force field that can definitely provide you with
explicit parameters for all possible combinations of those atoms.  But
you might look at the Dreiding force field proposed by Mayo, Olafson and
Goddard (_J. Phys. Chem._ *94*, 8897 (1990)) -- it provides a scheme to
extrapolate parameters from atomic hybridizations, bonding, and covalent
radii.  We use a related scheme to determine missing parameters in the
MM+ force field in our HyperChem software.

Regards,
Joel

------------
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Email to: [email-masked]