From owner-chemistry /at\ccl.net Thu May 25 03:26:00 2006 From: "=?ISO-8859-1?Q?Francisco_Partal_Ure=F1a?= fpartal*ujaen.es" To: CCL Subject: CCL: C2v pointgroup & coordinate system / unique choices of axis Message-Id: <-31835-060524123806-22010-BD4hHRCAZ8uGtGeniPptCA(!)server.ccl.net> X-Original-From: =?ISO-8859-1?Q?Francisco_Partal_Ure=F1a?= Content-Type: multipart/alternative; boundary="------------090403040607010501010202" Date: Wed, 24 May 2006 17:47:05 +0200 MIME-Version: 1.0 Sent to CCL by: =?ISO-8859-1?Q?Francisco_Partal_Ure=F1a?= [fpartal_._ujaen.es] This is a multi-part message in MIME format. --------------090403040607010501010202 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Dear Peter: The notation now accepted in group theory, known as Mulliken nomenclature, was published in J. Chem. Phys., 23 (11) 1955 1997-2011. In this report you can see that, for a C2v molecule (page 2002), z-axis is the axis of symmetry, and, in the case of water, x-axis is perpendicular to the molecular plane. Thus, the molecular plane is the yz. Cheers, ------------------------------------------------------------------------ Dr. Francisco Partal Ureña University of Jaén Department of Physical and Analytical Chemistry Campus Las Lagunillas E-23071 Jaén SPAIN Phone: +34-953-21 25 55 Fax: +34-953-21 29 40 Peter Burger chburger : aci.unizh.ch wrote: >Sent to CCL by: "Peter Burger" [chburger*aci.unizh.ch] >Dear CCLers, > >the following has puzzled me for a while... > >In the C2v point group different choices have been made in the >literature with regard to the x and y axis. > >Several books on symmetry and point groups provide >different answers... and sometimes even choose use >them either way in different chapters. > >For water for instance, most of them opt for the xz plane >as the molecular plane with y pependicular to it while others >refer to the yz as molecular plane with x perpendicular to it. > >This obviously leads to a change of the b1 and b2 symbols >and makes comparisons somehow complicated... > >So I guess my question is - use Al Cottons or Tinkhams >book as authorities? Is there somewhere the _real_ truth? > >Cheers > >Peter> > > > > > --------------090403040607010501010202 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit     Dear Peter:
    The notation now accepted in group theory, known as Mulliken nomenclature, was published in J. Chem. Phys., 23 (11)  1955  1997-2011. In this report you can see that, for a C2v molecule (page 2002), z-axis is the axis of symmetry, and, in the case of water, x-axis is perpendicular to the molecular plane. Thus, the molecular plane is the yz.
    Cheers,
 
Dr. Francisco Partal Ureña
University of Jaén
Department of Physical and Analytical Chemistry
Campus Las Lagunillas
E-23071 Jaén        SPAIN
Phone: +34-953-21 25 55
Fax: +34-953-21 29 40

Peter Burger chburger : aci.unizh.ch wrote:
Sent to CCL by: "Peter  Burger" [chburger*aci.unizh.ch]
Dear CCLers,

the following has puzzled me for a while...

In the C2v point group different choices have been made in the
literature with regard to the x and y axis.

Several books on symmetry and point groups provide
different answers... and sometimes even choose use
them either way in different chapters. 

For water for instance, most of them opt for the xz plane
as the molecular plane with y pependicular to it while others 
refer to the yz as molecular plane with x perpendicular to it. 

This obviously leads to a change of the b1 and b2 symbols
and makes comparisons somehow complicated... 

So I guess my question is - use Al Cottons or Tinkhams
book as authorities? Is there somewhere the _real_ truth?

Cheers

PeterE-mail to subscribers: CHEMISTRY(a)ccl.net or use:
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