Quantum theory and molecular structure

Extracting elements of molecular structure from the all-particle wave function

“…In a critical account Woolley 6 stated that "Quantum chemistry, however, has not as yet achieved this result, and instead the notion of molecular structure remains a stark mystery which [. .…”

“…of molecular symmetry, isomerism, and chirality can be reconstructed from the solutions of the all-particle Schrödinger equations. [6][7][8][9][10][11][12][13][14] In the current practice of quantum chemistry and electronic structure theory the BO or clamped nuclei approximation 4,15,16 is almost always introduced. In the first step it allows one to simplify the all-particle problem to a quantum mechanical problem of electrons moving in the external field of fixed, classical, distinguishable nuclei.…”

On the resolution of the optical rotatory power of chiral molecules into atomic terms. A study of hydrogen peroxide

“…A number of very general chemical, 28 physical, [29][30][31][32] and epistemological questions, see, for instance, a recent paper, 33 and references therein, are still wide open as regards the general understanding and implications of words like ''shape,'' ''bond,'' ''isomerism,'' ''symmetry,'' and phrases like ''bond lengths,'' ''bond angles,'' ''internal rotation barriers,'' ''nuclear vibrations,'' ''molecular chirality,'' ''lone-pair electrons,'' to quote but a few.…”

Quantum-Mechanical Definition of Atoms and Chemical Bonds in Molecules

“…Quantum-mechanical calculations of the properties of individual atoms and bonds in molecules from molecular wave functions are correspondingly thought to require introduction of subjective auxiliary conditions to achieve specificity [3], giving rise to many individual preferences and alternative possibilities, rendering a unique theoretical definition of molecular structure and chemical bonding continuingly elusive [4][5][6]. These…”