Subject: RE: Two close energy states

From: VITORGE Pierre 094605 <[email-masked]>
Date: Wed, 12 Sep 2001 14:13:05 +0200

For typically transition elements with d orbitals, the problem might also be
in the SCF calculation that oscillate between ground and exited state: check
occupancy in the output. In that case try (in gaussian) SCF=QC and
guess=read

Pierre Vitorge
CEA Saclay
Bat.450 pce 157D
DEN/DPC/SCPA/LCRE
UMR 8587 (Universite d'Evry-CNRS-CEA)
91191 Gif sur Yvette cedex
France

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-----Original Message-----
From: Herbert Fruchtl [mailto:[email-masked]]
Sent: Wednesday, September 12, 2001 11:10 AM
To: Antonio Morreale
Cc: [email-masked]
Subject: CCL:Two close energy states

It usually doesn't mean that there are two minima, but that your
optimization algorithm, in its choice of step size and direction, has
run into an endless loop. If the difference is too big to just call it
converged, you should discard your approximate Hessian and restart from
one of these points. If you can afford it, calculate a complete Hessian
first (possibly on a lower level of theory). It might help to change the
optimization algorithm, most programs offer more than one.

Antonio Morreale wrote:
> When doing some optimization, the energy values flutuates between two
> close values alternatively. As far as I know, it seems like there are
> two close energy states and the optimization algorithm is not able to
> choose for one. Is there any way to solve this problem?
>

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