Subject: bug in the G98 RHF ?

From: Arvydas Tamulis <tamulis!at!mserv.itpa.lt>
Date: Wed, 29 Oct 2003 16:54:44 +0200 (EET)

Dear Netters,

I am optimizing Peptide Nucleic Acids (PNA) fragments with G98 and compare
with optimization results obtained with GAMESS-US.

During optimization with G98 RHF 6-31G in the CytosinePNA fragment was
formed not expected H-bond with Cytosine and peptide group. Total energy
lowered down to -977.916 a.u.
While GAMESS-US RHF 6-31G optimization of CytosinePNA fragment gives total
energy equal to -938.906 a.u. and not appeared wrong H-bond between
Cytosine and peptide group.

By the way G98 B3LYP 6-31G optimization of CytosinePNA fragment does not
gives wrong H-bond between Cytosine and peptide group.

Interesting that AdeninePNA fragment optimization with G98 RHF 6-31G does
not gives wrong H-bond between Adenine and peptide group, while GAMESS-US
AdeninePNA RHF 6-31G optimized total energy is slightly lower.

So, it seems that sometimes during G98 RHF optimization might occur something
like wrong H-bond with very lowered total energy: difference arround 40 a.u.
Do it is bug in G98 or something else?

Best regards, Arvydas Tamulis
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                  Arvydas Tamulis

Doctor of Natural Sciences, senior research fellow

Institute of Theoretical Physics and Astronomy, Vilnius University,
Theoretical Molecular Electronics and Spintronics Research Group,
A. Gostauto 12, Vilnius 2600, Lithuania
e-mails: tamulis!at!itpa.lt  or  arvydas_tamulis!at!yahoo.com
WEBsite: http://www.itpa.lt/~tamulis/
fax: +370-5-2125361
Phones: +370-5-2625036  or  +370-5-2620861
Home address: Didlaukio 27-40, Vilnius 2057, Lithuania
Mobile phone: +370-69919397
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