Hyper-generalized-gradient functionals constructed from the Lieb-Oxford bound: implementation via local hybrids and...

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Theoretical Physics

Background:

• Odashima and Capelle (OC) developed a parameter-free correlation-only density functional in 2009.
• The original OC functional was size-inconsistent, limiting its practical application.
• Testing focused on total energies, not energy densities, hindering further development.

Purpose of the Study:

• To investigate the size-consistent variant of the OC density functional.
• To determine if the size-consistent OC functional, when combined with exact or semilocal exchange, forms a local hybrid (lh) functional.
• To evaluate the performance of nonempirical OC-lh functionals on molecular datasets.

Main Methods:

• Formulating the size-consistent OC functional using energy densities.
• Combining the OC correlation functional with exact and semilocal exchange functionals.
• Testing various nonempirical OC-lh functional variants on standard molecular test sets.

Main Results:

• The size-consistent OC functional with exact or semilocal exchange behaves as a local hybrid (lh) functional.
• No OC-lh variant achieved the accuracy of TPSS for enthalpies of formation.
• OC-lh correlation combined with exact exchange demonstrated accurate chemical reaction energy barriers.

Conclusions:

• The explored nonempirical OC-lh functional shows promise for calculating reaction energy barriers.
• Further research into near-self-consistency is important for nonlocal functionals.
• This work revisits and analyzes a previously published density functional design concept.