CCL: Comments on Orbitals - a practical approach of a theoretical chemist

I have been very busy recently with many other things.
 But I do wish to respond to the message posted by
 Victor Geskin on June 4, 03 in this List
 (http://www.ccl.net/cgi-bin/ccl/message.cgi?2003+06+04+001).
 In the first part of the message, a good picture was
 drawn about what theoretical papers SHOULD look like.
 I do not think there is anything that I cannot agree
 with in this part. In the second part, Victor made
 some very concise (at least to me) analyses about the
 essence of MOs. But in conclusion, he  consciously
 avoided any direct reply to whether the orbitals are
 real or not . I would conclude something very
 different.
 Based on his analyses, I would have to state clearly:
 Orbitals are mathematically real, but not physically.
 You don t know what orbitals mean physically unless
 you convert them to the electron density presentation.
 There is no physical reality corresponding to the
 naked orbitals. As some other people have already
 clearly stated in many occasions, orbitals have no
 physical meaning and no physical existence. Does it
 matter to be ambiguous?
 Let us apply some simple logic here:
 If orbitals are physically meaningless, orbital
 interaction is meaningless, orbital control is
 meaningless, and orbital stabilization and
 destabilization are meaningless. These are magic
 phrases to me. Does any body in this world really
 understand the orbital control theories in chemistry?
 In a discussion board of the Preprint Server, I
 compared orbitals to ghosts of no physically reality.
 As ghosts are physically meaningless, their fight,
 their interaction, and their control are meaningless
 and are beyond understanding in science. Some body
 wrote me a personal e-mail and said that orbitals and
 ghosts are different because orbitals are
 scientifically useful but ghosts are not. Orbitals are
 very very useful, but should be used appropriately.
 I greatly admire the realistic scientific attitudes of
 many greatest scientists such as Gell-Mann, Feynman,
 Dewar   If you don t understand, admit it. In his late
 stage of life, Dewar changed his mind, and clearly
 recognized the  hypnotic effect  of the orbital
 control theories in chemistry.
 Chemists  goal to understand chemical reactions is to
 understand how the electrons are relocated from old
 bonds to form new bonds; and what the kinetic and
 thermodynamic reasons are for the electron
 relocations. We wish to understand resisting forces
 and driving forces as the kinetic factors for the
 electron relocations. If we don t have this knowledge,
 we don t understand chemical reactions. It is simple
 and clear! This very important knowledge has been
 muddled up for decades as a result of our misuse of
 the orbital concept. How do orbitals control here? And
 control what?
 There is nothing wrong with Victor Geskin s choice of
 avoiding  any direct reply as soon as the orbital
 concept can be used correctly. But I am trying to
 emphasize the importance of being conceptually clear
 in the interpretation of our computational results.
 Our modern computational technologies have reached an
 astonishing level of high accuracy (thanks to the
 effort of computational chemists). Unfortunately, our
  words  have been very muddy for decades in the
 interpretation of complex chemical reactions such as
 concerted cycloadditions, and have caused conceptual
 confusions in our textbooks and the literature.
 Again, the philosophical questions remain. What do
 EXPLANATION and UNDERSTANDING really mean in science?
 What does MECHANISM mean in chemistry? Can we say that
 chemical reactions are controlled by orbital overlap
 integrals   mathematical operations or a human
 activity?
 I am far from being tired of this discussion, and wish
 to continue in any ways.
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