A new method for the calculation of atomic and local hardness

Abstract

The relationships between atomic hardness, atomic electronegativity, and electronic energy are considered and emphasized. A new method for calculating atomic hardness is described. The concept of local hardness is quantified through the calculation of a new variable named alfahardness. Atomic hardness and alfahardness are used for the calculation of both the mean molecular and local properties. The results obtained are discussed and a comparison made with the analogous quantities presented by Pearson. An algorithm has been realized and transformed into a computer routine for use within a CAOS program.

Does the Intra‐Atomic Deformation Energy of Interacting Quantum Atoms Represent Steric Energy?

“…The trend in B , shown in Table , supports this idea because B , and so the gradient of the intra‐atomic energy, increases from nitrogen to fluorine. This would suggest that nitrogen is the ‘softest’ of the three atoms and fluorine the ‘hardest’, which is in agreement with chemical intuition and the literature . This trend is seen more than once in our work; further details are shown in the Supporting Information in Table S7.…”

“…This would suggest that nitrogen is the 'softest' of the three atoms and fluorine the 'hardest', which is in agreement with chemical intuition and the literature. [50][51][52] This trend is seen more than once in our work; further details are shown in the Figure 4. Decomposed intra-atomic energy for the nitrogen atoms at q ¼ 90 � in the N 2 dimer theta scan (a); decomposed intra-atomic energy for the nitrogen atoms at q ¼ 10 � in the NH 3 dimer theta scan (b).…”

Generation of Chemical Transformations: Reaction Pathways Prediction and Synthesis Design

“…The methods implemented in the Beppe program to evaluate the reactivity are based on the calculations of atomic and molecular properties of reactants, defined in the frame of the density functional theory, including electronic energies, electronegativities, hardness, and other related reactivity descriptors [93,94]. They are used to select the reactive sites in the reactants and evaluate the imaginary intermediate, interpreted as an approximated model of the transition state.…”

A Theoretical‐Experimental Study on the Structure and Activity of Certain Quinolones and the Interaction of Their Cu(II)‐Complexes on a DNA Model

“…where g is the electronic chemical potential [21] of the species. Using again a finite difference approximation (assuming energy depends quadratically with N), (5) Atomic and molecular global hardnesses have been computed by different means [33][34][35][36] and the concept of hardness has been used to understand aromaticity in organic [37][38] and organometallic molecules [39]. The Relative hardness concept was introduced to characterize aromatic and anti-aromatic species [40] and the activation hardness index is useful to predict the orientation of electrophilic aromatic substitution in organic chemistry [41].…”