CCL:G: How to visualize a lone pair

 Sent to CCL by: "D. Afanasyev" [dafanasiev-*-ukr.net]
 Hello,
 you can't actually visualize a lone pair at all. It's a misinterpretation.
 What you can do is to visualize some orbital (say, NBO or PNBO of NBO analysis)
 which intuitively corresponds to a "lone pair" (and spatially
 resembles it, actually).
 You can do that either by means of GaussView or by means of NBOView.
 Or, alternatively, you can follow the way suggested by David and analyze the
 Laplacian field of your system. MOLDEN does some simple analysis of Laplacian
 from Gaussian/Gamess output files. AIM2000 also does stuff like that...
 Dmytro.
 **************************************
 *       Dmytro Afanasyev                        *
 *    Undergraduate Researcher            *
 *  Prof. H.F. Schaefer III group             *
 *Center for Computational Chemistry*
 *     University of Georgia                      *
 *       Athens, GA, 30602                        *
 **************************************
 -----Original Message-----
 > From: "Shobe, David dshobe{=}sud-chemieinc.com"
 <owner-chemistry===ccl.net>
 To: "Afanasyev, Dmitriy " <dafanasiev===ukr.net>
 Date: Wed, 19 Jul 2006 15:07:06 -0400
 Subject: CCL:G: How to visualize a lone pair
 > Sent to CCL by: "Shobe, David" [dshobe++sud-chemieinc.com]
 > Mateo,
 >
 > You don't really need COSMO-RS (a nice and useful program, so I'm told, but
 rather expensive) to find the lone pair direction.  All you need is a program
 that analyzes the electron density and finds the maximum of the Laplacian, which
 can usually be identified with an electron pair.  This maximum will be at a
 particular point in space, so the lone pair directionality follows naturally.
 >
 > --David Shobe, Ph.D., M.L.S.
 > Sьd-Chemie, Inc.
 > phone (502) 634-7409
 > fax (502) 634-7724
 >
 > Don't bother flaming me: I'm behind a firewall.
 >
 >
 >
 > -----Original Message-----
 > > From: owner-chemistry*o*ccl.net [mailto:owner-chemistry*o*ccl.net]
 > Sent: Wednesday, July 19, 2006 11:24 AM
 > To: Shobe, David
 > Subject: CCL:G: How to visualize a lone pair
 >
 > Sent to CCL by: Andreas Klamt [klamt=cosmologic.de] Dear Mateo,
 >
 > lone pairs and their directionalities can be very well identified in the
 VRML visualizations of the COSMO polarization charge density sigma on the COSMO
 surface. Many examples are given under http://www.cosmologic.de/ChemicalEngineering/visualization.html
 > (Please note that these are zipped VRML files. Normally they should simply
 open when you double click them from a browser which has a VRML plug in (e.g.
 CORTONA viewer from Parallel Graphics)
 >
 > Just look at the first example, phenoxymethyl-oxirane_sig, or at
 benzaldehyde, where you easily identify the lone-pair directions as red hot
 spots. Look at et3n (you have to rotate) and you will see the lonepair almost
 hidden between the et groups. Many more examples are given there. You can
 generate such VRMLs with our COSMOtherm software based on DFT COSMO tiles from
 TURBOMOLE, Gaussian03, or DMol.
 >
 > Our COSMO-RS method quite clearly turns out that some additional
 interaction (beyond electrostatics) is required for molecular surface with
 sigma> 0.008 e/Ang^2, strongly increasing with sigma.  Substantial hydrogen
 bonding only only occurs for sigma> 0.012 e/Ang^2. This can be found on lone
 pair regions of O, N, and S.
 >
 > Andreas
 >
 >
 >
 > > Sent to CCL by: Mateusz Witkowski [big_mateo++inbox.com]
 > >
 > > Hi,
 > > I'm interested in the directionality of O,N,S lone pairs in creation
 of hydrogen bonds.
 > > Is it possible to visualize a lone pair from QM results? If so, what
 should be done, which software should be used?
 > > What is your general impression about hydrogen bonds with XH-A angle
 ~100-120deg? Is there any border between HB and purely electrostatic
 interaction?
 > >
 > > TIA
 > > Mateo>
 > >
 > >
 > >
 > >
 > >
 >
 >
 > --
 >
 -----------------------------------------------------------------------------
 > Dr. habil. Andreas Klamt
 > COSMOlogic GmbH&CoKG
 > Burscheider Str. 515
 > 51381 Leverkusen, Germany
 >
 > Tel.: +49-2171-73168-1  Fax:  +49-2171-73168-9
 > e-mail: klamt:-:cosmologic.de
 > web:    www.cosmologic.de
 >
 -----------------------------------------------------------------------------
 > COSMOlogic
 >        Your Competent Partner for
 >        Computational Chemistry and Fluid Thermodynamics
 >
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