From owner-chemistry@ccl.net Thu Dec 1 15:27:00 2005 From: "Kirkpatrick, James james.kirkpatrick:imperial.ac.uk" To: CCL Subject: CCL: question on molecular orbitals in CO and NO Message-Id: <-30144-051201224202-21623-KdzIrYpOt9ShTJchp6vsRw]![server.ccl.net> X-Original-From: "Kirkpatrick, James" Date: Wed, 30 Nov 2005 14:19:30 -0000 Sent to CCL by: "Kirkpatrick, James" [james.kirkpatrick:+:imperial.ac.uk] hi, In my opinion, this discussion is again revolving aroung the theme of what does one mean by reality in science. "Are MOs real, or just mathematical constructs?" in my opinion contains two sides to it: a) are wavefunctions "real" b) are the approximations in treating the wavefunction of a molecule as made up of MOs appropriate. As regards a) I feel that most people involved in QM would say, yes MOs are real in the sense that very fundamental "mathematical constructs", such as momentum or mass or Temperature are real. As regards b) I imagine that it all depends on cicumstances: how are the MOs calculated, what system are we looking at... I imagine most people on this list have a better idea as to when particular model chemistries are appropriate and how to interpret MOs in each of those. So the statement "PES gives information about how MOs interact", in my opinion is perfectly justified, with the caveats that b) holds for the particular problem at hand. james -----Original Message----- From: Noko Phala nphala[#]angloresearch.com = Sent: Wed 11/30/2005 1:17 PM To: Kirkpatrick, James Subject: CCL: question on molecular orbitals in CO and NO Sent to CCL by: "Noko Phala" [nphala~~angloresearch.com] Being able to explain photoelectron spectra in terms of MO theory is not proof for existence of orbitals/orbital interactions. But perhaps the Nobel Laureate is proposing that the predictive power of the orbital concept so great that it is hard to not thing they are real.. _________________________ Dr Noko Phala Process Research Anglo Research=20 PO Box 106 Crown Mines 2025 Republic of South Africa Tel: +27 (11) 377 4817 e-mail: nphala\a/angloresearch.com=20