Average Local Ionization Energies as a Route to Intrinsic Atomic Electronegativities

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Atomic Physics

Background:

• Traditional electronegativity scales (Pauling, chemical potential, Allen's method) have limitations.
• Allen's scale, based on ionization energies, does not account for subshell interpenetration or d-electron enumeration ambiguities.
• Existing methods deviate from chemical experience or introduce ambiguity in defining atomic properties.

Purpose of the Study:

• To analyze and characterize a novel formulation of relative atomic electronegativities.
• To address the limitations of previous electronegativity scales, specifically subshell interpenetration and valence electron enumeration.
• To develop a chemically meaningful and computationally straightforward scale of atomic electronegativity.

Main Methods:

• Utilized the concept of average local ionization energy, I̅(r), defined by electronic density and orbital energies.
• Averaged I̅(r) over the outer surfaces (0.001 au electron density contour) of atoms.
• Employed various Hartree-Fock and density functional methods for computation, with a focus on the Perdew-Burke-Ernzerhof functional.

Main Results:

• The proposed method, based on averaged local ionization energy, yields a chemically meaningful scale of relative atomic electronegativities.
• This approach inherently avoids issues of subshell interpenetration and ambiguity in enumerating valence electrons.
• The Perdew-Burke-Ernzerhof functional produced the most chemically realistic results among the tested computational methods.

Conclusions:

• The new formulation provides a robust and conceptually clear method for determining atomic electronegativity.
• It offers a significant improvement over existing scales by accurately representing atomic electronic structure.
• This computational approach ensures consistent and straightforward treatment for all atoms, enhancing predictive power in chemical studies.