Increasing the applicability of density functional theory. II. Correlation potentials from the random phase...

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Density functional theory (DFT) calculations are sometimes mistrusted due to the unknown nature of exchange-correlation functionals.
• Wave-function theory (WFT) offers exact exchange-correlation functionals, providing a path to enhance DFT accuracy and reliability.
• The adiabatic-connection fluctuation-dissipation theorem connects exact functionals to the density-density response function.

Purpose of the Study:

• To investigate the use of WFT-derived correlation functionals within a DFT framework.
• To assess the accuracy of potentials derived from various WFT approximations (MBPT-2, RPA/ring-CCD, linear-CCD, CCD).
• To evaluate the performance of these potentials in approximating atomic properties, particularly ionization potentials.

Main Methods:

• Employed an optimized effective potential strategy to derive correlation potentials from WFT approximations.
• Performed Kohn-Sham self-consistent calculations using these derived potentials.
• Compared calculated potentials, total energies, and HOMO eigenvalues against exact values for spherical atoms.

Main Results:

• Developed and implemented correlation potentials corresponding to MBPT-2, RPA (ring-CCD), linear-CCD, and CCD.
• Analyzed the spatial behavior of these potentials and their impact on total energies and HOMO eigenvalues for spherical atoms.
• Demonstrated that self-consistent eigenvalues from these potentials approximate atomic ionization potentials, aligning with the ionization potential theorem.

Conclusions:

• WFT-based correlation functionals can be successfully integrated into DFT, enhancing the reliability of calculations.
• The developed potentials provide accurate approximations for atomic properties, including ionization potentials.
• This approach offers a promising avenue for improving the predictive power of DFT.