Density Scaling of Noninteracting Kinetic Energy Functionals

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Investigating kinetic energy functionals is crucial for accurate electronic structure calculations.
• Existing local functionals often fail to satisfy density scaling conditions, limiting their predictive power.

Purpose of the Study:

• To develop and evaluate a generalized gradient approximation (GGA) kinetic energy functional that incorporates an approximate density scaling condition.
• To assess the performance of this GGA functional in post-Kohn-Sham calculations for molecular systems.

Main Methods:

• A novel GGA functional was constructed, satisfying both density and coordinate scaling conditions.
• The functional's performance was tested using post-Kohn-Sham calculations on the G1 molecular set.
• Potential energy curves for CO, F2, and P2 were computed to evaluate binding properties.

Main Results:

• The proposed GGA functional demonstrated modest improvements in noninteracting kinetic energies compared to local functionals.
• The GGA functional successfully predicted binding for CO, F2, and P2, whereas local functionals yielded repulsive curves.
• Optimizing the GGA exponent for energy accuracy led to a violation of the density scaling condition and loss of binding for some diatomics.

Conclusions:

• Imposing an approximate density scaling condition on kinetic energy functionals can enhance their accuracy and predictive capabilities for molecular binding.
• The developed GGA functional offers a promising alternative to local functionals, though careful parameterization is needed to maintain desirable properties.
• Further research into density scaling conditions is warranted for developing more robust and accurate electronic structure methods.