RE: Two close energy states

[VITORGE Pierre 094605 <vitorge(-(at)-)azurite.cea.fr>]

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
 pierre.vitorge(-(at)-)cea.fr
 phone +33 169-08-32-65,
 secretary: +33 169-08-32-50,
 fax: +33 169-08-32-42
 http://perso.club-internet.fr/vitorgen/pierre/pierre.html
 -----Original Message-----
 From: Herbert Fruchtl [mailto:fruechtl(-(at)-)fecit.co.uk]
 Sent: Wednesday, September 12, 2001 11:10 AM
 To: Antonio Morreale
 Cc: chemistry(-(at)-)ccl.net
 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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