Towards Efficient Orbital-Dependent Density Functionals for Weak and Strong Correlation.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Density-functional theory (DFT) is a cornerstone of modern computational chemistry.
• Accurate modeling of electron correlation is crucial for predicting molecular properties.
• Existing DFT functionals struggle with certain challenging dissociation limits, such as H2 and H2+.

Purpose of the Study:

• To develop a novel paradigm for designing exchange-correlation functionals in DFT.
• To introduce an efficient variant of the Bethe-Goldstone equation (BGE2) for explicit electron pair correlation.
• To create a new orbital-dependent functional (ZRPS) that extends existing hybrid functionals.

Main Methods:

• Development of a screened second-order Bethe-Goldstone equation (sBGE2) approach.
• Explicitly correlating electron pairs using the sBGE2 method.
• Incorporation of sBGE2 as a building block into an orbital-dependent functional (ZRPS).

Main Results:

• The sBGE2 variant successfully addresses the dissociation of H2 and H2+, a significant challenge in DFT.
• The ZRPS functional, built upon sBGE2, shows remarkable and consistent improvements over other DFT functionals.
• ZRPS demonstrates enhanced performance across diverse chemical environments, from weakly to strongly correlated systems.

Conclusions:

• The sBGE2 approach offers a promising new direction for developing accurate exchange-correlation functionals.
• ZRPS represents a significant advancement in DFT, providing reliable predictions for a wide range of chemical systems.
• This work overcomes key limitations in current DFT methods, paving the way for more accurate computational chemistry.