Do the Local Softness and Hardness Indicate the Softest and Hardest Regions of a Molecule?

Torrent‐Sucarrat, Miquel; Proft, Frank De; Geerlings, Pau̧l; Ayers, Paul W.

doi:10.1002/chem.200800570

Cited by 84 publications

(69 citation statements)

References 119 publications

(174 reference statements)

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“…(It is important to emphasize that the function which correctly describes the local softness can be taken to be sðr * Þ ¼ Sf ðr * Þ only for soft systems. 22,23 ) Eqn (25) shows a kind of inverse relationship between local hardness and local softness, in accordance with intuitive expectations, since on the pointwise behavior of local softness (i.e. of the derivative of the density with respect to N), the pointwise behavior of the density does not have a direct effect.…”

Section: Local Hardness Through a Local Chemical Potentialsupporting

confidence: 83%

A new approach to local hardness

Gál

Geerlings

Proft

et al. 2011

Phys. Chem. Chem. Phys.

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The applicability of the local hardness as defined by the derivative of the chemical potential with respect to the electron density is undermined by an essential ambiguity arising from this definition. Further, the local quantity defined in this way does not integrate to the (global) hardness-in contrast with the local softness, which integrates to the softness. It has also been shown recently that with the conventional formulae, the largest values of local hardness do not necessarily correspond to the hardest regions of a molecule. Here, in an attempt to fix these drawbacks, we propose a new approach to define and evaluate the local hardness. We define a local chemical potential, utilizing the fact that the chemical potential emerges as the additive constant term in the number-conserving functional derivative of the energy density functional. Then, differentiation of this local chemical potential with respect to the number of electrons leads to a local hardness that integrates to the hardness, and possesses a favourable property; namely, within any given electron system, it is in a local inverse relation with the Fukui function, which is known to be a proper indicator of local softness in the case of soft systems. Numerical tests for a few selected molecules and a detailed analysis, comparing the new definition of local hardness with the previous ones, show promising results.

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Section: Local Hardness Through a Local Chemical Potentialsupporting

confidence: 83%

A new approach to local hardness

Gál

Geerlings

Proft

et al. 2011

Phys. Chem. Chem. Phys.

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“…An analysis of local electrophilicity (ω k + ) provides the information of a particular atomic site in a molecule being attacked by a nucleophile. This local property has been proposed as a better intermolecular reactivity index than the Fukui function itself for analyzing electrophile-nucleophile interactions becuase the Fukui function allows to compare the sites selectivity within a molecule, while for a comparison of the reactivity of a specific site on different molecules, it is more appropriate to use a property that includes intrinsic information of the systems studied [19][20][21][22]. In this context, the local softness and the local electrophilicity descriptors are suitable to explain hard-soft and electrophile-nucleophile interactions, respectively.…”

Section: Hmentioning

confidence: 99%

“…This contribution focuses on the structure and properties of the MPR 3 + fragments by reactivity indices as introduced through conceptual density functional theory (CDFT) [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the local reactivity of electrophiles of the type MPR 3 + (M = Cu, Ag, Au ;R = −H, -Me, -Ph)

2011

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Reactivity prediction in the series of MPR(3)(+) fragments ( M = Au, Ag, Cu; R = -H, -Me, -Ph) has been achieved at the ab initio (HF and MP2) and density functional theory (B3LYP and PBE) levels. We have used global and local descriptors based on conceptual DFT such as hardness, Fukui function and electrophilicity index. For all methods and fragments, we have found an equal trend in reactivity using both the global and local electrophilicity index: QR-AuPR(3)(+) > CuPR(3)(+) ≈ AgPR(3)(+) > NR-AuPR(3)(+). It is also found that the electrophilicity power decreases as the volume of R increases.

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“…The E dye is calculated by two approaches: a first level, applying molecular orbitals eigenvalues on the basis of Koopmans' theorem as IP ≈ -E HOMO [59]. This is accepted in the literature within the framework of the Conceptual Density Functional Theory (CDFT) [60,61]. A second level, the energy of the orbital that generates the transition in the band.…”

Section: Absorption Propertiesmentioning

confidence: 99%