Double-Hybrid Density Functional Theory within the Cluster-in-Molecule Local Correlation Framework for Large...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Double-hybrid density functional theory (DHDF) provides high accuracy for quantum chemical calculations.
• The computational cost of the perturbative second-order (PT2) correlation term limits DHDF to small systems.
• Accurate calculations for large molecular systems are crucial in various chemical applications.

Purpose of the Study:

• To develop a computationally efficient and accurate method for DHDF calculations on large molecular systems.
• To combine DHDF with a local correlation framework, creating the cluster-in-molecule double-hybrid density functional (CIM-DHDF) approach.
• To enable accurate PT2 energy evaluation for systems previously inaccessible to DHDF.

Main Methods:

• Development of the cluster-in-molecule double-hybrid density functional (CIM-DHDF) approach.
• Integration of DHDF with a local correlation framework for efficient PT2 energy calculations.
• Benchmark calculations using various basis sets and inclusion of diffuse functions.
• Validation against the domain-based local pair natural orbital coupled-cluster with singles, doubles, and perturbative triples [DLPNO-CCSD(T1)] method for reaction barrier heights.

Main Results:

• CIM-DHDF recovers over 99.9% of PT2 correlation energies compared to conventional DHDF methods.
• The method demonstrates high accuracy across different basis sets and for systems with diffuse functions.
• Calculations on large hydrogen-transfer reactions (up to 1443 atoms) show CIM-DHDF's scalability.
• Statistical analysis confirms the superior accuracy of double-hybrid functionals, particularly the XYG3 family, over conventional hybrids.

Conclusions:

• CIM-DHDF offers a scalable and reliable method for extending DHDF calculations to large molecular systems.
• The developed approach overcomes the computational limitations of traditional DHDF.
• This work paves the way for accurate quantum chemical studies on complex molecular systems previously beyond reach.