From: |
larry \\at// melanie.ucd.ie (Larry Cuffe) |
Date: |
Fri, 21 May 1999 10:45:05 +0100 (BST) |
Subject: |
Solvation and TS's |
Dear CCL
I'd apreciate it if anyone could give me pointers
to the relevent literature or their thoughts on the
following:
I have calculated Transistion states for some simple
molecules using the Onsager and SCIPCM models as implemented
in G94, using a dielectric constant of 80.25 to simulate
solvation in water.
Now my question: presumably when a molecule makes a transition
this hapens on a very short time scale. The high dielectric
constant of water is a DC value and coresponds to realignments
of molecules with a high dipole moment and also to some polarization
effects within the electronic structure of individual molecules.
The variation of dielectric constant with frequency has been measured
so we could choose a suitable lower dielectric constant with which
to optimize the transition state geometry, coresponding to the time
scale of the reaction. The question is how would we relate the results
of such a calculation to the stable molecular geometries at either side
of the TS for which a DC dielectric constant seems to be the most
apropriate choice.
The Transistion state of interest coresponds to an E-Z rotation about a
partial Double bond.
Any help would be apreciated
Larry Cuffe
(larry -x- at -x- melanie.ucd.ie)
Similar Messages
09/01/1995: Questions re dielec. const. & conformers
09/01/1995: Re: CCL:M:Questions re dielec. const. & conformers
01/10/1999: Re: CCL:RATE CONSTANT AND BARRIER-QUESTION
05/25/1995: Summary: Imaginary freq. and rate constant
08/04/1995: Re: CCL:Question about Electrostatics in Molecular Mechanics
01/07/1998: Chem Topic: Finding Transition Structures
02/21/1996: Summary: CRYSTAL & all
08/04/1995: Re: Question about Electrostatics in Molecular Mechanics
12/11/1995: Summary: Koopmans' Theorem and Neglect of Bond in CAChe MOPAC Input
12/16/1994: Spin contamination & AM1 "ROHF" versus UHF
Raw Message Text
|