Subject: Re: CCL:T1-diagnostic

From: Jordi Villa <[email-masked]>
Date: Sun, 11 Jun 2000 14:01:33 -0700

The T1 diagnostic was proposed, to the best of my knowledge, in the following
papers.

Lee, T. J.; Rice, J. E.; Scuseria, G. E.; Schaefer, H. F. Theor. Chim. Acta 1989,
75, 81.
Lee, T. J.; Taylor, P. R. Int. J. Quantum Chem. 1989, 23, 199.[CAS]

We particularly applied this diagnostic along a distinguished reaction coordinate
in a VTST calculation on the C2H4 + H reaction in

Jordi Villa, Jose C. Corchado, Angels Gonzalez-Lafont, Jose M. Lluch, and Donald G.
Truhlar* "Variational Transition-State Theory with Optimized Orientation of the
Dividing Surface and Semiclassical Tunneling Calculations for Deuterium and Muonium
Kinetic Isotope Effects in the Free Radical Association Reaction H + C2H4  C2H5".
J. Phys. Chem. A, 103 (26), 5061 -5074, 1999.

However, in this particular reaction, where we found an excessive value of T1 along
the reaction ccordinate, previous MRCI calculations by Hase et al. did not suppose
a significant improvement over our single determinant calculations, and thus,
further parametrization was necessary for obtaining a reliable potential energy
surface.

I hope this will help

Take care,

Jordi

Ohyun Kwon wrote:

> Dear CCLer's
> It is known that T1-diagnostic is used to determine whether single
> determinant wavefunctions can decribe molecular system properly or not.
> Could anybody give more details about T1-diagnostic such as how to
> calculate and how to apply?
> I will summarize it.
> Thank you in advance.
>
> yours
>
> Ohyun Kwon
> Department of Chemistry
> Auburn University
> Auburn, AL, 36849
>
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--
Jordi Villa i Freixa
Department of Chemistry, University of Southern California
3620 S McClintock Av. #418; Los Angeles, CA, USA, 90089-1062
Tlf: 1-(213)-740 7671 Fax: 1-(213)-740 2701
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