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.>