Subject: MP2 vs exact reaction energies

From: "Jon Andreas Støvneng" <[email-masked]>
Date: Wed, 20 Feb 2002 12:46:44 +0100

Dear CCL-readers,
consider a chemical reaction A + B --> AB.
Using MP2 with a good basis set, can any general
statements be made about the calculated reaction
energy E(AB)-E(A)-E(B) as compared with the
exact reaction energy?
For example: The reaction of 4 AlH with 4 H2AlOH
resulting in (Al2H4O)4 is calculated to be exothermic
by 329, 339, and 374 kcal/mol at the Hartree-Fock,
BP86, and MP2 level, respectively. What, if anything,
can then be said about the exact energy of this reaction?

sincerely,
------------------------------------
Jon Andreas Støvneng
Statoil Research Centre, N-7005 Trondheim, Norway
[email-masked]
Tel: +47 73584824   Fax: +47 73584345

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