Accuracy of charge densities in electronic structure calculations

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Accurate charge densities are fundamental for reliable electronic structure calculations.
• Charge densities critically influence predictions of chemical properties and atomic forces via the Hellmann-Feynman theorem.

Purpose of the Study:

• To assess the accuracy of charge densities derived from various density functional theory (DFT) exchange-correlation functionals.
• To compare DFT-derived charge densities against high-accuracy coupled cluster calculations.
• To evaluate the impact of basis set size on the accuracy of DFT charge densities.

Main Methods:

• Employed multiple density functional theory (DFT) exchange-correlation functionals.
• Utilized coupled cluster calculations with single and double excitations (CCSD) as a benchmark.
• Investigated the influence of different Gaussian basis set sizes on charge density accuracy.

Main Results:

• Modern DFT functionals, particularly meta-generalized gradient approximations and hybrid functionals, yield highly accurate charge densities.
• Basis set limitations necessitate the use of the largest available Gaussian basis sets to minimize basis set errors.
• DFT charge densities show excellent agreement with coupled cluster benchmark calculations when appropriate methods and basis sets are used.

Conclusions:

• Selecting appropriate DFT functionals and large basis sets is vital for obtaining high-precision charge densities.
• Accurate charge densities are essential for applications such as generating reference data for machine-learned potentials.
• This study validates advanced DFT methods for electronic structure calculations requiring precise charge density information.