Subject: RE: calculating polarizabilities

From: "Xavier ASSFELD" <Xavier.Assfeld-.at.-lctn.uhp-nancy.fr>
Date: Wed, 12 May 2004 10:01:47 +0200

Hi,

certainly the dianion is a closed shell molecule with 1A1 symmetry, and the
HOMO is degenerate n times. Hence in the anion, the subset of n orbitals
corresponding to the dianion HOMOs are no longer degenerate due to the
Hartree-Fock potential and thus the wavefunction does not have the right
symmetry and so any properties computed with that wavefunction won't have
the right symmetry neither.
If this is the case, use a CAS wavefunction or non-integer occupation
numbers.
Hope this helps.
Yours

                                      ...Xav

Pr. Xavier Assfeld                  Xavier.Assfeld-.at.-lctn.uhp-nancy.fr
Laboratoire de Chimie thiorique     (T) 33 3 83 68 43 82
Universiti Henri Poincari           (F) 33 3 83 68 43 71
F-54506 Nancy B.P. 239              http://www.lctn.uhp-nancy.fr

X> -----Message d'origine-----
X> De : Computational Chemistry List [mailto:chemistry-request-.at.-ccl.net]De
X> la part de Goedele Roos
X> Envoyi : mar. 11 mai 2004 17:56
X> @ : chemistry-.at.-ccl.net
X> Objet : CCL:calculating polarizabilities
X>
X>
X> Dear all,
X> Calculating the polarizability for a perfect tetrahedral
X> dianion, gives for the three diagonal elements of the
X> polarizability tensor: (XX)=(YY)=(ZZ).
X> But, when I calculate the polarizability of the mono-anion (of
X> the same system) on the optimized geometry of the dianion (thus
X> on the perfect tetrahedral geometry), the polarizabilitytensor
X> gives (XX)=(YY), but the (ZZ) component is different.
X> Has anyone also had this problems?
X> What can I do to solve this?
X> Can anyone give me some advise?
X> Thanks in advance for your help,
X> Sincerely Yours,
X> Goedele Roos
X>
X> Drs. Goedele Roos
X> Dienst Algemene Chemie (ALGC)
X> Vrije Universiteit Brussel (VUB)
X> Pleinlaan 2
X> B-1050 Brussels
X> Tel: 0032-2-629 35 16
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