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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: http://www.ccl.net/cgi-bin/ccl/send_ccl_message E-mail to administrators: CHEMISTRY-REQUEST(a)ccl.net or use http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtml Before posting, check wait time at: http://www.ccl.net Job: http://www.ccl.net/jobs Conferences: http://server.ccl.net/chemistry/announcements/conferences/ Search Messages: http://www.ccl.net/htdig (login: ccl, Password: search)http://www.ccl.net/spammers.txt RTFI: http://www.ccl.net/chemistry/aboutccl/instructions/">http://www.ccl.net/chemistry/aboutccl/instructions/ |