Hartree potential dependent exchange functional.

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Density Functional Theory

Background:

• Density functional theory (DFT) relies on accurate exchange-correlation functionals.
• Existing meta-generalized gradient approximation (meta-GGA) functionals have limitations in describing electron exchange interactions.

Purpose of the Study:

• Introduce a novel non-local ingredient, the reduced Hartree parameter, for constructing exchange functionals.
• Develop a new generation exchange functional, u-meta-GGA, by incorporating the reduced Hartree parameter with meta-GGA ingredients.

Main Methods:

• The reduced Hartree parameter, invariant under uniform density scaling, was utilized.
• The new functional, u-meta-GGA, was constructed using the electron density, its gradient, kinetic energy density, and the reduced Hartree parameter.

Main Results:

• The u-meta-GGA functional is exact for one- and two-electron systems.
• It demonstrates size-consistency, non-empirical nature, and satisfies uniform density scaling.
• The functional shows good accuracy for atoms, ions, jellium spheres, and molecules, often outperforming existing meta-GGA functionals.

Conclusions:

• The study validates the utility of the reduced Hartree parameter in developing exchange-correlation functionals.
• This work proposes a new rung on the Jacob's ladder for non-empirical density functionals.