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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. July 2003, Volume 2, Number 7, 454-474 |
Generalized Electronic Diabatic Theory and Chemical Topology: Conformational
Changes as a Transition in Electronic State
Orlando Tapia and Gustavo A. Arteca
Internet Electron. J. Mol. Des. 2003, 2, 454-474
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Abstract:
We present a simple conceptual scheme whereby changes in molecular quantum state
appear as Franck-Condon-like transitions driven by geometrical rearrangements of a
background of positive charges. The model is based upon two basic ingredients that
combine notions from quantum- and classical mechanics. First, we construct a complete
set of diabatic electronic wave functions, each of which is associated with a labeled
three-dimensional chemical graph. Secondly, we represent any electronic quantum state for the
molecular system as a superposition of these functions such that the coefficients for the
linear combination depend on the geometry of the set of positive charges. In contrast to
the standard Born-Oppenheimer approach, only the quantum state depends on the
location of these positive charges (and not the basis for the Hilbert space used to describe
any transition). The ideas are illustrated using a simple trans->cis transition. The
procedure can be applied in general to expose the fundamental electronic processes that
accompany real-space motion in more complicated molecular dynamics processes.
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