Effective local potentials for density and density-matrix functional approximations with non-negative screening...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density Functional Theory (DFT) is a powerful quantum mechanical modeling method.
• Improving the accuracy of spectral properties in DFT requires addressing self-interaction errors.
• Existing methods for error reduction involve constraints on the Kohn-Sham (KS) potential.

Purpose of the Study:

• To develop a more efficient and robust method for improving DFT accuracy.
• To introduce a novel variational quantity for constrained effective potential calculations.
• To reduce self-interaction errors in electronic structure calculations.

Main Methods:

• Introduced an effective "screening" amplitude, f, as the variational quantity.
• Defined the screening density as ρrep = f² to automatically satisfy positivity constraints.
• Applied the method to molecular calculations using DFT and reduced density matrix functional theory approximations.

Main Results:

• The new method, using ρrep = f², satisfies the positivity condition inherently.
• The minimization problem becomes more efficient and robust compared to previous approaches.
• The technique accurately reduces self-interaction errors in molecular calculations.

Conclusions:

• The proposed development offers an accurate and robust variant of the constrained effective potential method.
• This approach enhances the reliability of DFT calculations for spectral properties.
• The method shows promise for various electronic structure calculations in chemistry and physics.