From owner-chemistry@ccl.net Fri Nov  7 07:39:00 2008
From: "Gianluca Santarossa gianluca.santarossa[*]chem.ethz.ch" <owner-chemistry[a]server.ccl.net>
To: CCL
Subject: CCL:G: Relaxed scan using GDIIS with Gaussian
Message-Id: <-38055-081107061057-11439-DZuXyjDIq5ZRCSkF9O66hA[a]server.ccl.net>
X-Original-From: "Gianluca  Santarossa" <gianluca.santarossa(!)chem.ethz.ch>
Date: Fri, 7 Nov 2008 06:10:52 -0500


Sent to CCL by: "Gianluca  Santarossa" [gianluca.santarossa{=}chem.ethz.ch]
Dear Jose,
thanks for your help.

> You only have to include in calculation route the Modredundant keyword instead of Z-matrix. In 
the case of dihedral dih9=N1-N2-N3-N4 your input should be:

> #P PM3  opt=(tight,gdiis,modredundant) gfinput gfprint IOP(6/7=3) pop=full

> Then Z-matrix and geometrical parameters.
> (Blank line)
> * N2 N3 * R                  
> N1 N2 N3 N4 0.000 S 35 10.0
Nice trick. It perfectly worked.

> You have more information in G03 Manual, Opt keyword, Relaxed Potential Energy.
You're right, I should have read the manual more carefully, although it is my opinion that the lines 
you're referring to should be added to the examples at the end of the page.
It was confusing for me that the scan just worked with the Z-matrix keyword and without the GDIIS, 
while it did not when the GDIIS was turned on.

Anyway, sorry for the RTFM question, and thanks again.
Gianluca