CCL:G: Transition state calculation
- From: Jean Jules FIFEN <julesfifen===gmail.com>
- Subject: CCL:G: Transition state calculation
- Date: Fri, 5 Nov 2010 11:58:01 +0100
If what suggest by Jan does not work, also try modifying the
coordinates atom related to the last undesirable frequency mode and restart the
computation. For that, you could use an atom editor from gausview, adding the
opposite of amount of the higher deviations from zero on each coordinate.
If this does not also work, try doing the computation computing analytical
hessian at the first point or at any point if the previous does not success.
J. Jules Fifen.
On 5 November 2010
07:37, Dillen, Jan jlmd(!)sun.ac.za
JLMD(!)sun.ac.za <owner-chemistry ..
Sent to CCL by: "Dillen, Jan [jlmd:_:sun.ac.za]" <JLMD:_:sun.ac.za>
1. Animate the vibrations associated with the negative frequencies.
2. Decide from the movements of the atoms which modes have nothing to do with
the reaction coordinate that you associate with the SN2 reaction.
3. Distort the atoms with the eigenvectors of the unwanted negative frequencies
(meaning that you add the eigenvector times a constant [0.5 usually works fine]
to the coordinates). Alternatively, if these movements are e.g. rotations of
alkyl groups, you can give them a kick by changing the torsion angles with e.g.
4. Re-optimize with Opt(TS, NoEigenTest).
> From: owner-chemistry+jlmd==sun.ac.za#ccl.net
] On Behalf Of Henry Martinez hmartine * gmail.com
Sent: 04 November 2010 22:00
To: Dillen, Jan <jlmd#sun.ac.za
Subject: CCL:G: Transition state calculation
Sent to CCL by: "Henry Martinez" [hmartine###gmail.com
] Hi everyone, I am running
a Transition state calculation in Gaussian 03, using a b3lyp/ 3-21g freq
+237 75 21 61 39
+237 94 67 65 05
PO.BOX 454 Ngaoundere