Subject: ADF vs. G92/DFT energies

From: [email-masked] (Stephan Irle)
Date: Tue, 18 Jul 1995 18:08:42 +0100 (MESZ)

Dear Netters,

the bond energies from ADF/X-Alpha/DZP and
Gaussian/X-Alpha/6-31G** for H2 at the LDA-equilibrium
geometry in D(\inf h) symmetry (which is calculated
to be R=0.770 Angstrom from both programs) are
(in kcal/mol):

    ADF/X-Alpha/DZP      G92/DFT/XAlpha/6-31G**
        -150.1                   -84.8

(the G92-Value was obtained by subtracting
 the energy of 2 Hydrogen atoms from the
 total molecular energy, while the ADF value
 is just simply printed out; there is no
 error due to a mixup of unrestricted and
 restricted energies since H is a one-electron
 system).

This large difference requires explanation,
and most likely it is due to my ignorance that
these two values do not match. Any comments
or suggestions?

A second question: In dissociating H2 at the
restricted level of theory with same functionals
and basis sets as above, Gaussian shows the
correct, i.e. wrong dissociation limit. ADF
however does it wrong, i.e. the bond energy
approaches zero.

Thank you very much for your time and efforts

Stephan Irle
(Stud. of Prof. Lischka)

[email-masked]
 http://www.itc.univie.ac.at/~stephan/
 voice:+43/1/40480-679