Companions in the search

Reactivity and Charge Transfer Beyond the Parabolic Model: the “|Δμ| Big is Good” Principle

“…In this way, Sanderson's electronegativity equalization, [9,15] Pearson's hard/soft acid/base [16–24] (HSAB) and maximum hardness principles, [25–31] along with lesser known rules like the minimum electrophilicity principle, [32–40] have been shown to emanate from a common framework. In this regard, it is noteworthy to mention Parr and Yang's observation that we could provide a first‐principles justification of frontier molecular orbital theory if one was able to show that “given two moieties with generally similar dispositions for reacting with a given reagent, the reagent prefers the one which on the reagent's approach is associated with the maximum response of the system's chemical potential” [4,41] . This remark, which can be simply put as “|Δμ| big is good” (DMB), remained a conjecture for over 30 years, until we provided the first analytical arguments supporting it, and showing its connection with other reactivity principles [42–44] …”

“…In this regard, it is noteworthy to mention Parr and Yang's observation that we could provide a first-principles justification of frontier molecular orbital theory if one was able to show that "given two moieties with generally similar dispositions for reacting with a given reagent, the reagent prefers the one which on the reagent's approach is associated with the maximum response of the system's chemical potential". [4,41] This remark, which can be simply put as " j Δμ j big is good" (DMB), remained a conjecture for over 30 years, until we provided the first analytical arguments supporting it, and showing its connection with other reactivity principles. [42][43][44] From all of this it is clear that a fundamental problem in C-DFT is to have reliable models showing how the energy of a system changes with respect to its number of particles: the E vs. N problem.…”

Correlation Energy Densities: E Pluribus Unum

“…One of us (J.P.P) is grateful for the chances he has had to work with and talk with Professor Robert G. Parr (a "companion in the search" [39]) about density functional theory, a shared obsession.…”

Computing the Fukui Function in Solid-State Chemistry: Application to Alkaline Earth Oxides Bulk and Surfaces

“…Parr called this the "dµ big is good" rule; for which a recent proof is available. [11][12][13] Therefore, for a non-degenerate ground state, 14-17 a perturbation will be more effective in changing the chemical potential if such perturbation (a reagent) occurs in places where δµ δv( r) N is large.…”