Subject: RE: Can change of 0.02-0.05 Angstrams in bond to change radically system

From: "Shobe, Dave" <[email-masked]>
Date: Mon, 28 Aug 2000 11:49:40 -0400

In transition metal complexes the answer is "yes, sort of."  :-)   A small
change in bond length can lead to a change in the ground electronic state.
It's also very easy in ab initio calculations of transition metal complexes
for the wavefunction not to end up in the ground state.  There is an analogy
between calculation of the wavefunction and optimization of the geometry
(both involve varying parameters to minimize an energy), and it's possible
to end up at a "stationary point" which is a local but not the global
minimum.  It's also possible to end up with a wave function which is
analogous to a transition state or higher-order saddle point.  Gaussian has
a keyword "stable" to check for this.

--David Shobe
Sьd-Chemie Inc.
phone (502) 634-7409
fax     (502) 634-7724
email  [email-masked]

Any opinions herein are not necessarily representative of Sьd-Chemie.

-----Original Message-----
From: art' [mailto:[email-masked]]
Sent: Monday, August 28, 2000 7:39 AM
Cc: Computational Chemistry List
Subject: CCL:Can change of 0.02-0.05 Angstrams in bond to change
radically system

Hi, CCLers,

Can change of 0.02-0.05 Angstrams in bond length to change radically MO
system ?

I've got a serial of calculations whith growing one bond length in heme
system. For
some of calculated points the structure of HOMO were very diffrent from the
point
of view of contribution coefficients  of atoms.

Is it possible? Any opinion is wellcome.

By the way, interesting fatc that in the bond growth length by 0.3
Angstrams, there
alternating Single Point calculations, where convergence speed changes by
3-5 times
>...( for example .. - 25 -155 -40 -122 -50 -90 - ...). As I mentioned, the
step is
around 0.02 Angstrams. Is it not strange ??????

A.Ziemys

-= This is automatically added to each message by mailing script =-
[email-masked] -- To Everybody    |   [email-masked] -- To
Admins
[email-masked] -- HELP CHEMISTRY or HELP SEARCH
[email-masked] -- archive search    |    Gopher: gopher.ccl.net 70
Ftp: ftp.ccl.net  |  WWW: http://www.ccl.net/chemistry/   | Jan: [email-masked]