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Bond paths are not chemical bonds
1Department of Chemistry, McMaster University, Hamilton, ON L7L 2T1, Canada.
The Journal of Physical Chemistry. A
|September 3, 2009
Summary
Bond paths, not just chemical bonds, describe atomic interactions. This quantum mechanical approach offers a unified view of matter
Area of Science:
- Quantum Chemistry
- Materials Science
- Chemical Physics
Background:
- The definition of a bond path as a criterion for bonding between atoms is criticized for being mistakenly identified with a chemical bond.
- The concept of a chemical bond is considered too restrictive to explain the full spectrum of atomic and molecular interactions governing matter's properties.
- Van der Waals interactions are traditionally viewed as distinct from chemical bonding, contributing to condensed states alongside Pauli repulsions.
Purpose of the Study:
- To challenge criticisms of the bond path definition and establish its broader applicability beyond traditional chemical bonds.
- To demonstrate that bond paths, as measurable quantum mechanical observables, provide a more comprehensive framework for understanding interatomic interactions.
- To resolve interpretive dichotomies concerning interactions like van der Waals forces and their role in condensed matter.
Main Methods:
- Theoretical analysis defining a bond path operator as a Dirac observable.
- Application of quantum mechanical theorems to bond path properties.
- Experimental detection and property delineation of bond paths in molecular crystals, specifically analyzing spectroscopic data from dideuteriophenanthrene.
Main Results:
- Bond paths are shown to be applicable to all interactions determining matter's properties, not just chemical bonds.
- The bond path is established as a measurable expectation value of a quantum mechanical operator.
- Experimental evidence from molecular crystals, including dideuteriophenanthrene, supports the physical reality and significance of bond paths, refuting specific criticisms.
Conclusions:
- The bond path concept offers a more encompassing and experimentally verifiable criterion for interatomic interactions than the traditional chemical bond.
- Quantum mechanics provides a unified theoretical basis for understanding diverse interactions through the bond path operator.
- The study resolves long-standing interpretive issues regarding forces like van der Waals interactions and their contribution to material properties.
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