The chemical bond, despite being one of the most utilized phrases in explaining chemistry, is a rather illusive concept due its lack of clear definition. Most definitions involve extrinsic properties, such as the energy difference between a molecular state and some arbitrary dissociated state. Whether to define a bond as a physical entity or as a non-physical “bonding interaction” between atoms has fostered considerable debate in the theoretical chemistry community. One recent attempt to define where bonding interactions exist is through the Quantum Theory of Atoms in Molecules (QTAIM). QTAIM describes bonding interactions topologically, as 1D ridges of charge density that exist between nuclei. While this definition gives insight into types of bonding in many cases, it does not provide a picture for a physical bond. We have extended the QTAIM by describing bonds using a fully topological approach that utilizes 3D bond bundles which are bounded by zero-flux surfaces. This definition has the advantage of viewing a bond as a physical observable in the charge density. Furthermore, by decomposing bond bundles into smaller volumes also bounded by zero-flux surfaces we are able to describe bonds as an intrinsic property of the charge density. An initial study of the charge and kinetic energy density distributions in the bond bundles of simple diatomic molecules will be presented.

In search of an intrinsic chemical bond

249th National Meeting (2015)

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