[molpro-user] Radical Cation Wavefunction

[Tony Stüker]

Hi Alan

The state symmetry is determined by the direct product[1] of all
electrons of the system.

You will see that the direct product of a closed shell system is always
the lowest irrep in the character table.

Examples for a c2v system:

Closed shell system: ^1A1

Dublett state with one unpaired electron in a mo with b1 symmetry, the
state symmetry would be ^2B1

Triplett state with two unpaired electrons in mos with a1 and b1
symmetry: A2 x B1 = B2

Hope that helps a little bit.

Cheers, Tony

[1] https://www.staff.ncl.ac.uk/j.p.goss/symmetry/Products.html

On 04/16/2016 02:00 PM, MD Simulation wrote:
> Hi Joachim,
> 
> Thanks for your reply, it's very helpful.
> 
> How do I know the state symmetry before the calculation?  I would like
> to read more about how to determine the proper symmetry, are there
> specific terms I could look up for the wave function symmetry?
> 
> I've read this section of the quickstart manual several times:
> https://www.molpro.net/info/2012.1/doc/quickstart/node11.html
> I've also read:
> 
> https://www.molpro.net/info/2012.1/doc/manual/node33.html#sec:symmetry
> https://www.molpro.net/info/2012.1/doc/manual/node34.html
> 
> 
> Again, thank you for your help,
> Alan
> 
> 
> 
> 
> On Sat, Apr 16, 2016 at 6:27 AM, Hans-Joachim Werner
> <werner at theochem.uni-stuttgart.de
> <mailto:werner at theochem.uni-stuttgart.de>> wrote:
> 
>     Hi,
>     the Hartree-Fock program at least tries to find the lowest state and
>     to determine the state symmetry automatically. But this is based on
>     orbital energies and there
>     is no guarantee that the correct state is always found. The meaning
>     of the state symmetries is explained in the manual, see also the
>     quickstart manual for examples. For example, in a linear molecule
>     oriented along the z-axis, a Sigma^+, state has symmetry 1, Pi_x,
>     Pi_y (symmetries 2,3), Sigma^- symmetry 4, Delta_{x^2-y^2} symmetry
>     1, Delta_{xy} symmetry 4 (but note that some of these states require
>     more than 1 Slater determinant, and then mcscf muust be used for a
>     proper description).
>     Best regards
>     Joachim Werner
>     ---
>     Prof. Dr. Hans-Joachim Werner
>     Institute for Theoretical Chemistry
>     University of Stuttgart
>     Pfaffenwaldring 55
>     D-70569 Stuttgart
>     Tel: +49 711 / 685 64400
>     Fax: +49 711 / 685 64442
>     email: werner at theochem.uni-stuttgart.de
>     <mailto:werner at theochem.uni-stuttgart.de>
> 
> 
>     > Am 15.04.2016 um 14:56 schrieb MD Simulation
>     <mdsimulationgroup at gmail.com <mailto:mdsimulationgroup at gmail.com>>:
>     >
>     > Hello Molpro Users,
>     >
>     > I'm very new Molpro but have used NWChem and Gaussian quite a
>     bit.  I'm attempting to use CCSD(T) on a radical cation organic
>     compound.  My question is, how necessary is it to set the
>     wavefunction symmetry and occupied orbitals (I'm not certain how to
>     determine either of those) in the WF card and OCC card?  In NWChem
>     or Gaussian I would simply set the charge (equal to 1) and
>     multiplicity (equal to 2), so in this case will I get the correct
>     results by simply using:
>     >
>     > """
>     > wf,charge=1,spin=1
>     > """
>     >
>     > Thanks for the help.  And as a side note, Molpro is really fast!
>     >
>     > Cheers,
>     > Alan
>     > _______________________________________________
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> 
> 
> 
> 
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