Size-Consistent Adiabatic Connection Functionals via Orbital-Based Matrix Interpolation.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density functional theory (DFT) is a powerful tool for electronic structure calculations.
• Developing accurate and size-consistent correlation functionals remains a challenge in DFT.
• Existing methods struggle with self-interaction errors and accuracy for diverse chemical systems.

Purpose of the Study:

• Introduce a novel, size-consistent, and orbital-invariant formalism for constructing correlation functionals.
• Develop a method that overcomes limitations of previous adiabatic connection functionals.
• Improve the accuracy and reliability of DFT calculations for molecular systems and the uniform electron gas.

Main Methods:

• Constructing correlation energy matrices in the occupied orbital space for weak and strong correlation limits.
• Implementing an orbital-based size-consistent matrix interpolation (OSMI) approach.
• Designing a nonempirical adiabatic connection and a one-parameter strong-interaction limit functional.

Main Results:

• OSMI accurately reproduces the correlation energy of the uniform electron gas across various densities.
• OSMI demonstrates higher accuracy than MP2 and nonempirical density functionals on the GMTKN55 thermochemistry database.
• OSMI achieves excellent predictions for reaction barrier heights with average errors below 2 kcal mol⁻¹.
• OSMI improves the trade-off between fractional spin and charge errors in bond dissociation curves.

Conclusions:

• OSMI offers a robust framework for accurate electronic structure calculations.
• The method successfully addresses size-consistency and self-interaction errors.
• OSMI shows potential for studying complex heterogeneous chemical systems.