Density cumulant functional theory: first implementation and benchmark results for the DCFT-06 model

Area of Science:

• Quantum chemistry
• Computational physics
• Theoretical chemistry

Background:

• Density cumulant functional theory (DCFT) is a theoretical framework for electronic structure.
• Previous implementations were limited, hindering its application.
• Accurate prediction of molecular interactions is crucial in chemistry and physics.

Purpose of the Study:

• To implement Density Cumulant Functional Theory (DCFT-06) for the first time.
• To benchmark DCFT-06 performance for atoms and diatomic molecules.
• To assess its capabilities for nonbonded and bonded interactions.

Main Methods:

• Implementation of the DCFT-06 formalism.
• Benchmark calculations on atomic and diatomic molecular systems.
• Comparison with established methods like Coupled Cluster theory with Single and Double excitations (CCSD).

Main Results:

• DCFT-06 demonstrates performance similar to CCSD in describing dispersion interactions.
• For covalently bonded systems, DCFT-06 predicts properties of at least CCSD quality near equilibrium.
• The computational scaling is O(N^6), similar to CCSD, but with potential advantages.

Conclusions:

• DCFT-06 is a viable and accurate method for electronic structure calculations.
• It shows promise as an alternative to CCSD, particularly due to its favorable properties.
• Further exploration of DCFT-06 for larger systems is warranted.