>From szilagyi@miat0.vein.hu Wed Jan 12 04:18:43 1994
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To: chemistry@ccl.net
Cc: szilagyi@miat0.vein.hu
Subject: METMOD1 force field
Date: Wed, 12 Jan 94 10:01:11 +0100
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Status: RO
Dear Netters,
I am sending now, the first part of the METMOD1 force field.
Anyone can use it who has the PCMODEL V4.0. If someone has only the
MM2 (or similar force field MMX, MM+, etc.), he/she can very easy
install the additional parameters (marked with C). Do not need to
reoptimize it.
Part I. Modelling of WCl4CR1R2 complexes
PARAM.NEW file:
-------------------------------------------------------------------------------
MMX (1986)
(THE PARAMETERS INDICATED WITH AN ASTERISK ARE NOT FINAL.)
0 ATOMS INDICATE GENERALIZED PARAMETERS
TORSIONAL PARAMETERS
ANGLE V1 V2 V3
TOR 1 1- 1- 1- 1 0.200 0.270 0.093
---------- rest deleted ------------
Some instruction in use
I marked with a letter C the new (additional) parameters.
Lets see the general formula of the complex:
Cla The structure is very close to the
Cle | R1 trigonal bipyramidal coordination.
>W=Cc< (but there some significant distortion)
Cle | R2
Cla
Atom types:
W tunsgten 31
Cle equatorial Cl 12
Cla axial Cl 59
Cc carbene C 2
anything else is MMX default.
--------------------------------------------
stuff deleted
--------------------------------------------
The average and RMS fitting error are less than 0.05 A !!
(Large and significant difference is in the W-Cla bond
length. From the ab initio calcns. it seems to be longer
then the equatorial one. In the literature we did not
find any similar effect, so at this time we did not make
any difference between these two bond lenght)
There is a possibility to manage with alpha hydrogen
coordination to metal atom. The user needs redefine
the alpha carbon and hydrogen and the carbene group will
rotate to minimise the distance between W and alpha-H.
(In this particular application it is not really important
but it will be in other systems.)
Test files:
--------------------------------------------
stuff deleted
--------------------------------------------
Please find the rotational barriers, the precise description of the
parameter optimization in the published papers.
If you want to minimized the structures you need to retype the atoms
and if you want to display it you need to "backtype" the atoms, of
course.
If something is missing or not clear please write me
Rob
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