Re: CCL:Seeing molecular orbitals?

 Hi Jens (Denmark)
 You said <But strictly speaking, this does not turn MOs into
 
 observable quantities; MOs have no physical existence>
I am new to computational chemistry. My background is medicine and human ecology in Australia. Your post is the first indicator I have seen over a wide range of CCL and books which signals caution. I am overwhelmed by the volume and intensity of work on the methodology and mensuration of molecules, as if that were the end in itself. No where do I see any concern for a Philosophy of Computational Chemistry, which addresses just what is computational chemistry and what its purpose might be in our Universe. I cannot believe the objective is merely to measure everything and simply document these data?
Even at my early stage, I am seriously pondering writing material jointly with my academic supervisor who is a computational chemist, which sets out the link (as I see it) between cosmology, quantum theory, relativity and higher dimensions theory on the one hand and computational chemistry on the other. I think molecules are the beautiful building blocks of our Universe and created for a purpose. I decline the view molecules are just chance particles. I suspect from my reading of CCL, my intention may be seen as revolutionary if not outrageous and could well cause an uproar? 
 Best wishes from Australia
 Dr Henry Pang
 Postgraduate Student, Computational Chemistry
 Faculty of Science, Information Technology and Education
 Northern Territory University
 PO Box U273 NT University 0815 Australia
 Mobile 61 419 682121 Fax 61 8 8946 6847 hpangaus "-at-" hotmail.com
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 From: "Jens Spanget-Larsen" <jsl "-at-" virgil.ruc.dk>
 To: CHEMISTRY "-at-" ccl.net
 Subject: CCL:Seeing molecular orbitals?
 Date: Thu, 20 Jul 2000 10:43:01 +0100
 Dear CCL:
 In a recent, most interesting publication ('Seeing molecular orbitals',
Chem.Phys.Letters 321, 78-82 [2000]) scanning tunneling microscopy is used to 
 observe the shapes of single molecular orbitals of the fullerene C60:
   "..the scanning tunneling microscope (STM) is probing a single molecular
   orbital (MO)."
 However, this reminds me of previous statements in the literature some time
ago, associated with the advent of molecular photoelectron spectroscopy, f.i.
"Chemists can see the orbital structure of even fairly large molecules and no 
   longer have to rely on the predictions of theoreticians"
   "Photoelectron spectroscopy has demonstrated experimentally to chemists,
   physicists and other sceptics that molecular orbitals really do exist"
 I wonder whether this is acceptable terminology, considering the fact
 that molecular orbitals are model constructs; they are not physical
 observables. By using approximations, such as Koopmans' approximation, many
 experimental observations can be conveniently interpreted in terms of
 theoretical MO data. But strictly speaking, this does not turn MOs into
 observable quantities; MOs have no physical existence.
 Any comments?
 Yours, Jens >--<
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