Curing basis-set convergence of wave-function theory using density-functional theory: A systematically improvable...

Area of Science:

• Quantum Chemistry
• Computational Physics

Background:

• Basis-set incompleteness is a major source of error in wave-function theory (WFT) calculations.
• Accurate electronic structure calculations are crucial for understanding chemical phenomena.

Purpose of the Study:

• To develop a method that corrects for basis-set errors in WFT using density-functional theory (DFT).
• To introduce an adaptive range-separation parameter for improved accuracy.

Main Methods:

• Utilizing the Levy-Lieb formulation of DFT to derive exact equations.
• Coupling DFT and WFT via a real-space representation of the electron-electron Coulomb operator.
• Developing a local-density approximation for a complementary functional in FCI and SCI methods.

Main Results:

• The proposed DFT-WFT method significantly accelerates basis-set convergence for total energies and energy differences.
• Achieved sub-kca/mol accuracy using the aug-cc-pVTZ basis set, comparable to near full-configuration-interaction (FCI) results with larger basis sets.
• Demonstrated improved accuracy for total energies and ionization potentials in atomic systems.

Conclusions:

• The DFT correction effectively mitigates basis-set errors in WFT calculations.
• This approach offers a computationally efficient route to high-accuracy results in quantum chemistry.
• The method shows great promise for accurate predictions of molecular properties.