A focus on penetration index - a new descriptor of chemical bonding

Electron clouds surrounding atoms interpenetrate in a molecule, due to weak van der Waals interactions or formation of a genuine chemical bond. Now, Alvarez and Echeverría (S. Alvarez, J. Echeverría, Chem. Sci. , 2023, https://doi.org/10.1039/D3SC02238B ) suggest a simple descriptor of how deep this interpenetration is, calling it a penetration index , i [Å]. This property may easily be related to a combined thickness of the van der Waals regions of two bond-forming atoms, thus giving rise to a dimensionless penetration index , p AB [%]. How far this new index may take us will be discussed in this article. Electron clouds surrounding atoms interpenetrate in a molecule, due to weak van der Waals interactions or formation of a genuine chemical bond. Now, Alvarez and Echeverría have suggested a simple descriptor of how deep this interpenetration is, and called it a penetration index , i .