Poisson-transformed density fitting in relativistic four-component Dirac-Kohn-Sham theory

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Relativistic Quantum Mechanics

Background:

• Relativistic density functional theory (DFT) is crucial for heavy elements.
• Accurate Coulomb interaction calculations are computationally demanding.
• Density fitting approximations can accelerate these calculations.

Purpose of the Study:

• To implement and optimize the density fitting approach for Coulomb interactions in four-component relativistic DFT.
• To develop a simple and efficient method for generating auxiliary basis sets using the Poisson equation.
• To assess the accuracy and efficiency of the proposed method for spectroscopic and energetic properties.

Main Methods:

• Utilized the Poisson equation to generate auxiliary basis sets for density fitting.
• Simplified electron repulsion integrals using the generated auxiliary basis sets.
• Employed standard Coulomb fitting sets in conjunction with Poisson-generated sets.
• Calculated spectroscopic properties, energetics, and reaction pathways for gold-containing systems.

Main Results:

• Demonstrated that a small number of standard auxiliary functions suffice for high accuracy with Poisson-generated sets.
• Achieved fitting accuracy comparable to or better than standard methods.
• Showcased efficiency in calculations for gold dimer, CsAu, and a Au(H2O)9+ cluster.
• Illustrated favorable scaling behavior for gold clusters.

Conclusions:

• The proposed Poisson-based density fitting method is efficient and accurate for relativistic DFT.
• This approach offers computational advantages, particularly for systems with heavy elements like gold.
• The method shows potential for application to relativistic exchange-correlation problems.