Subject: Re: CCL:Is TD or Zindo better than CIS?

From: Arvydas Tamulis <[email-masked]>
Date: Tue, 23 Oct 2001 08:50:39 +0200 (EET)

Dear Professor Hutchison and other CCL contributors,

Thank you for your professional explanation and making clear many aspects
of comparison of ZINDO, HF-CIS and DFT-TD, HF-TD.

Having in mind all your and your colleagues mentioned negative points of
ZINDO, HF-CIS and HF-TD, DFT-TD, we started to write DFT-TD that should be
suitable for the calculations of electron charge transfer in excited
states in large supermolecules (molecular devices, see our WEBsite:
www.itpa.lt/~tamulis/).

I need your consultations: did we started right relaying on DFT-TD using
gradient-corrected functionals (see C. Van Cailie, R.D. Amos, Chem. Phys.
Lett., v. 317 (2000) p. 159-164)?

Would you please to say that calculation algorithms of molecular integrals
over Gaussian basis functions are correct in article:
M. Dupuis, J. Rys, H. King, J. Chem. Phys. v. 65, p. 111-116, 1976,  or
presently exist better published algorithms?

Finally we need well described publications on SCF DIIS algorithm and
algorithm for convertion four centers integrals to three centers
integrals.

We plan to run this our writting program on our having heterogenic
cluster: Alpha XP1000 + 6x(AMD 1.2 GHz; 512 Mb; 40 Gb) that should be extended
in the future.

With best regards, Arvydas Tamulis
************************************************
           Arvydas Tamulis

Doctor of Natural Sciences, senior research fellow

Institute of Theoretical Physics and Astronomy,
Theoretical Molecular Electronics Research Group,
A. Gostauto 12, Vilnius 2600, Lithuania
e-mail: [email-masked]; WEBsite: http://www.itpa.lt/~tamulis/
fax: +(370-2)-225361  or  +(370-2)-224694
Phone: +(370-2)-620861
Home address: Didlaukio 27-40, Vilnius 2057, Lithuania
Phone: +370-9919397
*****************************************************

On Mon, 22 Oct 2001, Geoff Hutchison wrote:

> At 1:25 PM -0400 10/22/01, Shobe, Dave wrote:
> >spectrum.  Gaussian has two other methods (neither of which I've used) for
> >calculating excited states: Zindo and TD.  Are these significatnly better
> >than CIS?  Zindo being a semiempirical method, is it only good for certain
> >kinds of molecules?  Should I be looking at programs other than Gaussian for
> >this type of calculation?
>
> It's strange this should come up as I'm working on a manuscript along
> these lines for a certain set of molecules. But first there's a
> nomenclature issue. Normally when people say "Zindo," they mean
> "INDO/S CIS," and so you can't compare "Zindo" to "CIS." Also, I'm
> not quite sure I know what you mean when you say "TD" since you
> usually refer to TD-HF or TD-DFT for time-dependent HF or time
> dependent DFT.
>
> If you compare Zindo CIS to HF-CIS for most neutral organic
> molecules, you'll find Zindo is more accurate. If you compare TD-HF
> (say the RPA) to HF-CIS, the HF-RPA is better--no surprise since the
> RPA is one step past the Tamm-Dancoff approximation (CIS). But HF-RPA
> is not as good as Zindo for most neutral organic molecules.
>
> TD-DFT seems to be slightly worse than Zindo for neutral organic
> molecules, but not by much.
>
> Also keep in mind that Zindo CIS as a semiempirical method sometimes
> incorrectly identifies the composition of certain excitations even if
> the energy is pretty good.
>
> Can't say how Gaussian does on these sorts of things--we can't get it
> here. As Mark Thompson pointed out, you can also go beyond CIS to
> CISD, etc. The original ZINDO program from Zerner does let you do
> things like this, though YMMV. Other programs as well have CISD,
> CISDT and other higher-order methods. (Dalton springs to mind.)
>
> --
> --
> -Geoff Hutchison	<[email-masked]>
> Ratner/Marks Groups	(847) 491-3295
> Northwestern Chemistry	http://www.chem.nwu.edu/
>
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>
>
>
>

---

From: "Mark A. Thompson" <[email-masked]>
Date: Tue, 23 Oct 2001 07:26:05 -0700

The nomenclature issue surrounding Zindo is a bit confusing.

Zindo originally was just a program name for the code produced by Mike
Zerner's group.  Over time, Zindo became synonymous with the INDO/s-CIS
method that Mike and Joanna Ridley developed in the 70's.  The Zindo
Hamiltonian is a Hartree-Fock semiempirical method.  It solves the same
matrix equations as any other Hartree-Fock method, albeit with
approximations in how the elements of the Fock matrix are generated and
usually assuming the overlap matrix is unity.  So, confusingly, Zindo means
not only the ground state Hamiltonian, but the approach (INDO/s-CIS) to get
the excited states.  The more important issue to me, is that after all these
years, the method has shown itself invaluable to an increasing number of
chemistry problems from non-linear optical effects, organometallic systems,
solvent effects, to the large calculations Mike and I did on the
photosynthetic reaction center some years ago.

Mark

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