From owner-chemistry@ccl.net Thu Feb 22 12:50:00 2007
From: "Joseph Han jhh3851.:.yahoo.com" <owner-chemistry^-^server.ccl.net>
To: CCL
Subject: CCL: the cases which B3LYP method or 6-31+G** basis set overestimates
Message-Id: <-33677-070221132334-25243-E0q8qCdrFQFobsmUgWleHQ^-^server.ccl.net>
X-Original-From: Joseph Han <jhh3851#%#yahoo.com>
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Date: Wed, 21 Feb 2007 09:23:17 -0800 (PST)
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Sent to CCL by: Joseph Han [jhh3851[-]yahoo.com]

If the reaction is not gas-phase, another possibility might be the effect of
solvent molecules either through a PCM type effect or else explicitly binding
to the complex to stabilize the transition state.  

Joseph

--- "GÜL ALTINBAŞ galtinbas _ gmail.com" <owner-chemistry*ccl.net> wrote:

> Hi all,
> I have been studying on the mechanism of an organic reaction which  occurs
> at room temperature. I am using B3LYP/6-31+G** basis set since our
> structures are charged. We proposed two plausible mechanisms.  I found the
> activation barriers of the rate determining steps of these mechanisms as 45
> and 58  kcal/mole. These energy are  too high for the reaction at room
> temperature. My question is:
> "Does anyone know a special case in which B3LYP method or 6-31+G(d,p) basis
> set overestimates the activation barrier?"
> I am waiting for your answers or any suggestions.
> Best regards
> Gul
> -- 
> Gül Altinbas Ozpinar
> Research Assistant
> Marmara University
> Arts&Sciences Faculty
> Chemistry Department
> Göztepe Campus 34722
> Istanbul / Turkey
> Phone No: +90 216 347 96 41 - 1167
> Fax No: + 90 216 347 87 83
>