CCL: spin contamination and S**2



Hello Telkuni,

yes, "S squared" of 0.5 for a singlet, and 1.2 for a doublet are spin contaminated.
There are some correction schemes available to "project out" the pure state;
we've recently reported some results for iron porphyrins in:
J. Phys. Chem. A 2005, 109, 3411

On Sep 18, 2005, at 10:28 PM, CCL wrote:

Sent to CCL by: "Telkuni Tsuru" [telkuni^^venus.dti.ne.jp]

--Replace strange characters with the "at" sign to recover email address--.

Hello, Callers.

I like to ask the relationship between the spin contamination and
S**2 value.

As mentioned before, S**2 shows the spin state, singlet(=0 [+/- 10%]),
doublet (=0.75 [+/- 10%]), triplet (=2.0 [+/- 10%]), etc. When one
molecule's multiplicity is singlet and its S**2 is 0.5, can I say that
the molecule has spin contamination ?
And the same manner, the multiplicity is doublet and its S**2 is 1.2,
can I say that the molecule has spin contamination too ?

(What should I call "S**2"? Is it "S star 2"?)

All responses, I will appreciate.
I will summarize them and send to CCL.


Thanks in advance
---------------------------------------------------
Telkuni Tsuru telkuni[#]venus.dti.ne.jp



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