From chemistry-request "-at-" ccl.net Wed May 28 03:50:08 2003 Received: from smtp2.ruc.dk (smtp2.ruc.dk [130.225.220.70]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4S7o8KY001057 for ; Wed, 28 May 2003 03:50:08 -0400 Received: by smtp2.ruc.dk (Postfix, from userid 504) id 77641C7EE7B; Wed, 28 May 2003 09:50:07 +0200 (CEST) Received: from virgil.ruc.dk (virgil.ruc.dk [130.225.220.110]) by smtp2.ruc.dk (Postfix) with ESMTP id 62388C7EE78 for ; Wed, 28 May 2003 09:50:06 +0200 (CEST) Received: from VIRGIL/SpoolDir by virgil.ruc.dk (Mercury 1.47); 28 May 03 09:50:06 +0100 Received: from SpoolDir by VIRGIL (Mercury 1.47); 28 May 03 09:50:00 +0100 From: "Jens Spanget-Larsen" Organization: Roskilde Universitetscenter To: CHEMISTRY|at|ccl.net Date: Wed, 28 May 2003 09:49:49 +0100 Subject: Orbitals Reply-To: spanget|at|ruc.dk Message-ID: <3ED4782D.12504.2B5051 _-at-_)localhost> X-Confirm-Reading-To: spanget|at|ruc.dk X-pmrqc: 1 Priority: normal X-mailer: Pegasus Mail for Windows (v4.01) X-Spam-Status: No, hits=-3.2 required=5.0 tests=QUOTED_EMAIL_TEXT version=2.53 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) Mikael Johansson: > On Tue, 27 May 2003, Jens Spanget-Larsen wrote: > > > And in principle, MOs are not physical quantities; they are model > > constructions, and as such they have no physical reality and they > > cannot be observed experimentally. > > Well, there is a lot of discussion in the literature on this topic. > A few good examples, biased towards my thinking, could be: > > [1] Stowasser and Hoffmann, "What Do the Kohn-Sham Orbitals and > Eigenvalues Mean?", J.Am.Chem.Soc. 121 (1999) 3414-3420. > [2] Baerends, Theor.Chem.Acc. 103 (2000) 265-269. > > Have a nice day, > Mikael J. > http://www.helsinki.fi/~mpjohans/ Dear Mikael, Yes, it is true, there has been some discussion on the status of the MO concept. But to me, there can be no doubt: In principle, orbitals are one-electron wavefunctions, and for a many-electron system, they do by definition NOT correspond to physical reality. However, they are extremely useful models, as we all know. The usefulness of the MO concept in rationalizing a lot of chemistry and spectroscopy sometimes leads people to think of MOs as physical quantities, rather than simplified models. Do you think my point of view is erroneous? Yours, Jens >--< =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= JENS SPANGET-LARSEN Office: +45 4674 2710 Department of Chemistry Fax: +45 4674 3011 Roskilde University (RUC) Mobile: +45 2320 6246 P.O.Box 260 E-Mail: spanget|at|ruc.dk DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=