A non-decomposable approximation on the complete density function space for the non-additive kinetic potential.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Density Functional Theory

Background:

• Non-additive kinetic energy (NA K E) potentials are crucial for accurate electronic structure calculations.
• Existing approximations can suffer from artificial charge leakage due to shallow wells.
• The need for improved NA K E approximations that preserve exact properties is recognized.

Purpose of the Study:

• To construct a new, non-decomposable approximation for the non-additive kinetic energy potential.
• To ensure the new approximation covers the complete function space for exponentially decaying densities.
• To eliminate artificial shallow wells and improve the range of applicability of semilocal functionals.

Main Methods:

• Construction of a non-decomposable NA K E potential approximation.
• Introduction and analysis of a differential operator kernel Dγ[ρ] dependent on γ.
• Selection of γ = 1 to ensure solution functions span the complete space of molecular electron densities.
• Numerical validation using the Wesolowski and Weber procedure.

Main Results:

• The new approximation preserves the reciprocal singularity for exponentially decaying densities.
• Artificial shallow wells, causing charge leak, are eliminated.
• Numerical performance demonstrates enhanced accuracy and applicability of semilocal functionals.
• The developed approximation increases the range of applicability for semilocal functionals.

Conclusions:

• The new non-decomposable NA K E potential approximation is a significant improvement over previous methods.
• This work provides a more robust and accurate tool for electronic structure calculations.
• The enhanced semilocal functionals broaden the scope of computational chemistry studies.