From owner-chemistry@ccl.net Fri Feb 17 22:22:00 2006 From: "Mark Zottola mzottola[*]gmail.com" To: CCL Subject: CCL: Lowdin and Mulliken population Message-Id: <-30920-060217222046-5877-xBBwPnn+gjcOCqifGi3PHQ:+:server.ccl.net> X-Original-From: "Mark Zottola" Content-Type: multipart/alternative; boundary="----=_Part_1536_5827512.1140232840051" Date: Fri, 17 Feb 2006 22:20:40 -0500 MIME-Version: 1.0 Sent to CCL by: "Mark Zottola" [mzottola!=!gmail.com] ------=_Part_1536_5827512.1140232840051 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Point taken, but it should be noted that the Voronoi and Hirshfeld charges do use an arbitrary means for beginning their electron density partitioning. The advantage AIM charges have is that they are unambiguous, based on the determination of the zero-flux surface. And it is this unambiguous definition that makes the AIM charges a true physical observabl= e quantity. I would be happy to discuss this further offline as the conflict between MO theorists and electron density topology/AIM theorists make religious wars look tame. Mark On 2/17/06, Nuno A. G. Bandeira nuno.bandeira%ist.utl.pt < owner-chemistry%x%ccl.net> wrote: > > Sent to CCL by: "Nuno A. G. Bandeira" [nuno.bandeira|,|ist.utl.pt] > Mark Zottola mzottolaa/gmail.com wrote: > > > Noticeably lacking from this discussion is consideration of electron > > density-based charges. Using the AIM formalism, one does get an exact > and > > proper partitioning of electron density, providing charges that can be > > experimentally verified. The discussion of Lowdin, Mulliken or NBO > charges > > is really which kluge works best for a given application. > > Hirshfeld and Voronoi charges are based on electron density. In fact > Hirshfeld was a crystallographer and he wrote his original paper taking > into account the electron density taken from crystallographic > measurements. > > Regards, > > -- > Nuno A. G. Bandeira, AMRSC > Graduate researcher and molecular sculptor > Inorganic and Theoretical Chemistry Group, > Faculty of Science > University of Lisbon - C8 building, Campo Grande, > 1749-016 Lisbon,Portugal > http://cqb.fc.ul.pt/intheochem/nuno.html > Doctoral student -,- IST,Lisbon > -- > > > > -=3D This is automatically added to each message by the mailing script = =3D-> > > > ------=_Part_1536_5827512.1140232840051 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Point taken, but it should be noted that the Voronoi and Hirshfeld cha= rges do use an arbitrary means for beginning their electron density partiti= oning.  The advantage AIM charges have is that they are unambiguous, b= ased on the determination of the zero-flux surface.  And it is this un= ambiguous definition that makes the AIM charges a true physical observable = quantity.
 
I would be happy to discuss this further offline as the conflict betwe= en MO theorists and electron density topology/AIM theorists make religious = wars look tame.

Mark
 
On 2/17/06, = Nuno A. G. Bandeira nuno.bandeira%ist.utl.pt <owner-chemistry%x%ccl.net> wrote:
Sent to CCL by: "Nuno A. G.= Bandeira" [nuno.bandeira|,|ist.utl.pt]
Mark Zottola mzottolaa/gmai= l.com wrote:

> Noticeably lacking from this discussion is consideration of el= ectron
> density-based charges.  Using the AIM formalism, o= ne does get an exact and
> proper partitioning of electron density, p= roviding charges that can be
> experimentally verified.  The discussion of Lowdin, Mull= iken or NBO charges
> is really which kluge works best for a given ap= plication.

Hirshfeld and Voronoi charges are based on electron densi= ty. In fact
Hirshfeld was a crystallographer and he wrote his original paper taking=
into account the electron density taken from crystallographic measureme= nts.

Regards,

--
Nuno A. G. Bandeira, AMRSC
Graduate re= searcher and molecular sculptor
Inorganic and Theoretical Chemistry Group,
Faculty of Science
Uni= versity of Lisbon - C8 building, Campo Grande,
1749-016 Lisbon,Portugal<= br>http://cqb.fc.ul.pt= /intheochem/nuno.html
Doctoral student -,- IST,Lisbon
--



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