From owner-chemistry _-at-_)ccl.net Mon Oct  3 14:17:00 2005
From: "Mariusz Sterzel msterzel(a)buffalo.edu" <owner-chemistry#server.ccl.net>
To: CCL
Subject: CCL: What keeps a molecule adsorbed?
Message-Id: <-29478-051003141526-25902-oFUubBI8b8HYIDholY4Ciw#server.ccl.net>
X-Original-From: Mariusz Sterzel <msterzel(_)buffalo.edu>
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Date: Mon, 3 Oct 2005 13:15:18 -0400 (EDT)
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Sent to CCL by: Mariusz Sterzel [msterzel^_^buffalo.edu]
Dear Noel,

Following Ruedenberg, the simple answer is electrons 
kinetic energy. For more details look at K. Ruedenberg, Reviews of Modern 
Physics, 34(2):326-376, (1962) and M.S. Gordon, J.H.Jensen, Theoretical 
Chemistry Accounts, 103:248-251, (2000)


Mariusz

--
Mariusz Sterzel
Email: msterzel/^at^\buffalo.edu



On Mon, 3 Oct 2005, Noel O Boyle noel.oboyle2|*|mail.dcu.ie wrote:

>
> Sent to CCL by: "Noel O'Boyle" [noel.oboyle2++mail.dcu.ie]
> Dear all,
>
> I have been trying to explain the results of a DFT study (using G03)
> where a molecule adsorbs onto a gold cluster through its nitrogen atom.
>
> I created an isosurface of the change in the electron density associated
> with the adsorption (by calculating the electron densities of the
> molecule and the gold cluster separately at the geometry of the adsorbed
> system). This shows that electron density *decreases* in the area
> between the adsorbate and the surface. This is the opposite of what I
> expected.
>
> A paper by Bilic, Reimers, Hush and Hafner (JCP, 2002, 116, 8981) shows
> the same effect for ammonia on an infinite surface of gold(111). It
> shows the same result, and says that this is evidence that covalent
> bonding effects are not so important (they also have other evidence).
>
> It seems that I do not understand bonding very well - what keeps the
> molecule stuck to the surface, if it isn't a shared electron or two?
>
> Regards,
> Noel
> -- 
> Dr. Noel M. O'Boyle,
> Group of Dr. John Mitchell (http://www-mitchell.ch.cam.ac.uk),
> Unilever Centre for Molecular Science Informatics,
> Dept. of Chemistry,
> University of Cambridge,
> U.K.>
>
>
>
>