From owner-chemistry@ccl.net Fri Feb 20 14:10:01 2015
From: "Stefan Grimme grimme..thch.uni-bonn.de" <owner-chemistry^server.ccl.net>
To: CCL
Subject: CCL: QTAIM or else
Message-Id: <-51056-150220140729-15540-PvGgqO7L8yCUPoaohBCZ6g^server.ccl.net>
X-Original-From: "Stefan  Grimme" <grimme^_^thch.uni-bonn.de>
Date: Fri, 20 Feb 2015 14:07:28 -0500


Sent to CCL by: "Stefan  Grimme" [grimme- -thch.uni-bonn.de]

>I do not at all agree with the statement of Prof Grimme saying that
>"I don't think that QTAIM can give you a reasonable answer because its >predictions are in serious disagreement with experimental data for a >related case,"

>This paper has been rebutted by Bader and also by myself in
>The QTAIM Perspective of Chemical Bonding , P.L.A. Popelier in 
>The Nature of the Chemical Bond Revisited, Chapter 8, pp 271-308 (pp 1-38), >Eds. G. Frenking and S. Shaik, Wiley-VCH, 2014.    

>For your convenience let me quote a relevant passage from this Chapter:

>"Moreover, it should be emphasized that the German authors invoked the
>architecture of the MM3 force field in order to separate molecular potential energy into chemically meaningful parts."

A force-field was merely used for further analysis but the main point of the
paper, the EXPERIMENTALLY OBSERVED tiny splitting between the symmetric and anti-symmetric stretch C-D vibrations in dideutero-phenanthrene is not
affected or related to its use. The strong interpretation of the QTAIM that energy local lowerings ("bonding") have a chemical meaning is falsified by the experiment in the original paper. According to to QTAIM one would expect a large splitting (of +/- sign depending if its repulsive or attractive) but practically nothing (about 10 cm^-1) is seen. I don't seen any reasonable rebuttal to this fact. As mentioned already in the original work, an energy lowering of 7-8 kcal/mol for this D...D interaction as predicted by QTAIM should lead to  splittings on the order of hundreds of cm^-1.


Cheers!
Stefan