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Updated: Jul 14, 2026

Quantitative Hardness Measurement by Instrumented AFM-indentation
Published on: November 22, 2016
Quantum similarity study of atoms: a bridge between hardness and similarity indices
A Borgoo1, M Torrent-Sucarrat, F De Proft
1Department of General Chemistry (ALGC), Vrije Universiteit Brussel (VUB, Free University of Brussels), Pleinlaan 2, 1050 Brussels, Belgium.
Abstract:
A hardness based similarity index for studying the quantum similarity for atoms is analyzed. The investigation of hardness and Fukui functions of atoms leads to the construction of a quantum similarity measure, which can be interpreted as a quantified comparison of chemical reactivity of atoms. Evaluation of the new measure reveals periodic tendencies throughout Mendeleev's table. Moreover on the diagonal the global hardness was recovered. Considering a corresponding quantum similarity index reveals that renormalization of the measure can mask periodic patterns. The hardness was calculated for atoms with nuclear charge 3
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