Simple and Accurate Exchange Energy for Density Functional Theory.

Area of Science:

• Computational chemistry
• Quantum mechanics
• Density functional theory

Background:

• Accurate prediction of molecular properties is crucial in chemistry.
• Existing methods face challenges in balancing accuracy and computational cost.
• Density functional theory (DFT) is a widely used quantum mechanical modeling method.

Purpose of the Study:

• To develop a novel non-empirical exchange functional for improved accuracy in DFT calculations.
• To combine the new exchange functional with a recently proposed correlation functional.
• To evaluate the performance of the combined functional for molecular total energy predictions.

Main Methods:

• An interpolation between the slowly varying and asymptotic limits of electron density was used to construct the exchange functional.
• The functional construction was inspired by the exact exchange functional of a hydrogen atom.
• The new exchange functional was combined with a recently developed correlation functional for testing.

Main Results:

• The exchange-correlation functional demonstrated significantly higher accuracy in predicting total energies for 56 small molecules compared to Quantum Monte Carlo methods.
• For first-row molecules, total energy predictions were four times more accurate.
• Errors in core electron exchange energies for second-row molecules were corrected, yielding state-of-the-art molecular total energy predictions.

Conclusions:

• The proposed non-empirical exchange functional, when combined with the recent correlation functional, provides highly accurate molecular total energy predictions.
• This approach achieves superior accuracy for both first- and second-row molecules with minimal computational cost.
• While bond energies, zero point energies, and dipole moments were calculated, they did not show superior performance compared to other methods.