Subject: AM1, PM3, and radicals

From: Bruce Allan Palfey <[email-masked]>
Date: Tue, 5 Sep 2000 12:11:10 -0400 (EDT)

Can anyone tell me if the energies obtained from semiempirical
calculations, especially the AM1 and PM3 methods, are reliable for
radicals, including radical anions?  Can they be compared to energies of
corresponding singlet compounds in a meaningful way?  References would be
appreciated.  Thanks in advance.

Bruce Palfey
University of Michigan
Department of Biological Chemistry
Ann Arbor, MI 48109-0606

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From: Russ Johnson <[email-masked]>
Date: Wed, 06 Sep 2000 09:30:31 -0400

Hello,

	The Computational Chemistry Comparison and Benchmark Database (CCCBDB) has over 70 radicals species with calculations performed at AM1 and PM3. You can compare atomization energies or other reactions and see how well those methods perform versus experiment or versus ab initio methods. The URL is:

http://srdata.nist.gov/cccbdb/

Unfortunately there are no anions in the CCCBDB yet.

<color><param>0000,0000,ffff</param>Dr. Russell D. Johnson III

Research Chemist

National Institute of Standards and Technology

Computational Chemistry Group

100 Bureau Drive, Stop 8380

Gaithersburg, MD 20899-8380

voice 301+975-2513     fax  301+869-4020

email: [email-masked]</color>