Subject: CCL:potential surfaces

From: MARSAL Philippe <[email-masked]>
Date: Fri, 05 Mar 1999 13:50:15 +0100

-Dear ccls

I would like to understand why when working in cartesian coordinates and
diagonalizing the hessian matrix on a potential surface at a point witch
is not a stationnary point I find only 3 zero eigenvalues (what about
the rotations).

Thanks- 
_______________________________________________________________________

                      MARSAL Philippe
                 "Laboratoire de Chimie Theorique"
                   SREP CNRS - UMR 6517
	        "Chimie, Biologie et Radicaux libres"
		Universite de Provence	Faculte de Saint-Jerome
		Avenue Escadrille Normandie - Niemen
		13397 MARSEILLE Cedex 20 - France
                Phone # : (ext) + 04-91-28-84-14         
                FAX   # : (ext) + 04-91-98-85-12    
________________________________________________________________________

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From: Konrad Hinsen <[email-masked]>
Date: Fri, 5 Mar 1999 19:53:39 +0100

> is not a stationnary point I find only 3 zero eigenvalues (what about

Not being at a stationary point means that there is a non-zero energy
gradient. So when you rotate the whole system, the energy gradient
follows the rotation as well. The difference between the rotated and
the original gradient is thus not zero, meaning that this motion does
not correspond to a zero eigenvalue.
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