Subject: Why aren't DFT methods suitable for long distance interactions?

From: Yubo Fan <[email-masked]>
Date: Thu, 14 Oct 1999 15:47:47 +0800

Hi, everyone,

Many articles and books say that DFT methods are not suitable for
intermolecular interaction calculations. That means I can use DFT to
calculate many H-bonding or Pi-Pi systems. I don't know the reason. Can
anybody explain it?

Thank you very much

Y. Fan

=============================================================
Yubo Fan                         Email: [email-masked]
Organic Synthesis Lab
The Department of Chemistry
Fudan University                 Phone: 8621-65648139
No. 220 Handan Road              Fax:   8621-65641740
Shanghai, 200433
P. R. China
=============================================================

---

From: [email-masked]
Date: Thu, 14 Oct 1999 13:50:42 +0200 (MSZ)

There is no such general statement. It depends on the physics of the 
interaction. For H-bonded systems for example, there is *experience* that
DFT does not work too well, or that it is acceptable only for specific
functionals.

For dispersion forces on the other hand, it is clear that DFT cannot treat
them: although the opposite is claimed from time to time, it should be
obvious that there is no long-range correlation in local or gradient-corrected
functionals.

---------------------------+------------------------------------------------
Christoph van Wullen       | Fon (University):  +49 234 700 6485
Theoretical Chemistry      | Fax (University):  +49 234 709 4109
Ruhr-Universitaet          | Fon/Fax (private): +49 234 33 22 75 
D-44780 Bochum, Germany    | eMail: [email-masked]
---------------------------+------------------------------------------------