Re: CCL:Defining orbitals



 Jim Kress wrote:
 
Why not do an MCSCF calculation? It would solve the single reference MP2 issues and allow you to examine all the states of interest.
 
also an MCSCF would allow you to calculate specific states only by the use of the IOp(4/72=IJKLMN) keyword
 
 Jim
     ------------------------------------------------------------------------
     *From:* Christopher Thompson [mailto:cdth)at(unimelb.edu.au]
     *Sent:* Monday, June 13, 2005 9:46 PM
     *To:* chemistry)at(ccl.net
     *Subject:* CCL:Defining orbitals
     David,
     You interpreted my question correctly. Without going into the
     experiment in detail ... we generate Li-(H2O)n clusters and record
     their infrared spectrum. The source of Li- can potentially create
     Li- anions in more than the lowest energy singlet state. It
     appears that the symmetry of the clusters is not the same for
     different e spin states on the Li- >... an excellent way to
     differentiate species in vibrational spectroscopy. It would be
     nice to characterise the different triplet states comprehensively.
     Cheers,
     Chris
     On 14/06/2005, at 3:40 AM, Shobe, David wrote:
         Yes, but...I think he wants to study what would more correctly
 
be called a particular state of Li anion triplet.
 
I don't remember how Gaussian treats the degeneracy of the
         three p orbitals.  If Gaussian just arbitrarily picks one of
         the three p orbitals, no special manipulation is needed; but
         if the HOMO is a mixture of px, py, and pz it's a different
         story...
 
         --David Shobe, Ph.D., M.L.S.
         S|d-Chemie, Inc.
         phone (502) 634-7409
         fax (502) 634-7724
         Don't bother flaming me: I'm behind a firewall.
         *From:* Computational Chemistry List
         [mailto:chemistry-request)at(ccl.net] *On Behalf Of *Wayne Steinmetz
         *Sent:* Friday, June 10, 2005 4:46 PM
         *To:* chemistry)at(ccl.net
         *Subject:* CCL:Defining orbitals
         The electrons belong to the entire atom and are not
         constrained to any orbital.  One uses orbitals to construct
         the wave function.  One must be sure that the set of orbitals,
         i.e. the basis set, is sufficiently flexible to describe
         completely the molecular species.  You are dealing with an
         atomic species so a polarization basis set is probably not needed.
 
Wayne E. Steinmetz
         Carnegie Professor of Chemistry
         Woodbadge Course Director
         Chemistry Department
         Pomona College
         645 North College Avenue
         Claremont, California 91711-6338
         USA
         phone: 1-909-621-8447
         FAX: 1-909-707-7726
         Email: wsteinmetz)at(pomona.edu
         WWW: pages.pomona.edu/~wsteinmetz
 
-----Original Message-----
         *From:* Computational Chemistry List
         [mailto:chemistry-request)at(ccl.net] *On Behalf Of *Christopher
         Thompson
         *Sent:* Thursday, June 09, 2005 6:09 PM
         *To:* chemistry)at(ccl.net
         *Subject:* CCL:Defining orbitals
 
Gday, I would like to do an MP2 calc on a Li- species in triplet state. With one electron in the s orbital and one in a p orbital,
         how can you constrain the electron to say the px orbital?
 
Cheers,
         cdth)at(unimelb.edu.au
 
Christopher Thompson
         Laser Spectroscopy Group
         School of Chemistry
         University of Melbourne
     Dr Christopher Thompson
     Laser Spectroscopy Group
     School of Chemistry
     University of Melbourne
     VIC, Australia, 3010.
     Ph. +61 3 8344 8163
     Fax. +61 3 9347 5180
 
 --
 James Kirkpatrick
 -------------------------------------------
 Centre for Electronic Materials and devices
 Imperial College
 -------------------------------------------
 020 759 47519