Subject: Re: CCL:Orbitals and Reality

From: "Dr. N. SUKUMAR" <nagams-.at.-rpi.edu>
Date: Fri, 30 May 2003 0:40:40 EDT

Dr. Noodleman, I hate to quibble with what you've written, since you've
expressed things so clearly, and I agree with most of what you say, but...

> In general, I think of orbitals as somewhat real, less than electron
> densities, or atoms,
> but more than Lewis bond structures (at least, most of the time).

I think of orbitals as somewhat LESS real than "Lewis bond structures"
since in most cases the latter can be uniquely derived from topological
analysis of the (real) electron-density, i.e. from the gradient paths and
critical points thereof, whereas individual one-electron orbitals for
many-electron systems, however useful they might be, are quite arbitrary;
orbitals are solutions to a mathematical equation for a model system and
will differ depending upon the model employed (Huckel, Hartree-Fock,
Kohn-Sham, natural orbitals).

With all due respect to the stalwarts of quantum mechanics, it makes little
sense today to use terms like "physical reality" which cannot be defined
with the degree of rigor we expect in science, without employing circular
logic. And how to define "think" and "I" without invoking open systems and
wavefunction collapse? Why, I'll be glad if we can all agree on the meaning
of the word "is"!

Dr. N. Sukumar
http://www.drugmining.com/
Visiting Scientist
Rensselaer Department of Chemistry and
Wadsworth Center, New York State Dept.of Health