Stowasser and Hoffmann say virtually as much in this article.Many scientific concepts have proved useful in the history of science but were eventually found to be redundant or non-existent. For example, caloric, phlogiston, the ether etc.
But is there a sense in which the Kohn-Sham orbitals are "more real" than the orbitals used in ab initio work? This seems to be the claim of some recent authors.
But then we get into another odd notion, namely that having physical reality comes in degrees!
please see,The Recently Claimed Observation of Atomic Orbitals and Some Related Philosophical Issues", Philosophy of Science, 68,(Proceedings) S76-S88, N. Koertge, ed. Philosophy of Science Association, East Lansing, MI, (2001)
Have Orbitals Really Been Observed?, Journal of Chemical Education, 77, 1492-1494, (2000)
although neither of these articles discuss the reality of orbitals of the DFT variety.
regards, eric scerriI would like to invite contibutions of articles or comments on this question to the journal Foundations of Chemistry (see below for info).
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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.
-- Dr. Eric Scerri , UCLA, Department of Chemistry & Biochemistry, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569 USA E-mail : scerri.-at-.chem.ucla.edu tel: 310 206 7443 fax: 310 206 2061 Web Page: http://www.chem.ucla.edu/dept/Faculty/scerri/index.html Editor of Foundations of Chemistry http://www.kluweronline.com/issn/1386-4238 Also see International Society for the Philosophy of Chemistry http://www.georgetown.edu/earleyj/ISPC.html