The densities produced by the density functional theory: comparison to full configuration interaction

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density functional theory (DFT) is a powerful computational tool.
• Accurate electronic charge density is crucial for understanding molecular properties.
• Evaluating DFT functionals is essential for reliable predictions.

Purpose of the Study:

• To assess the accuracy of popular DFT functionals in reproducing electronic charge densities.
• To compare the performance of different exchange-correlation functionals.
• To benchmark DFT results against high-level quantum chemistry methods.

Main Methods:

• Calculated electronic charge densities for small molecules (He, H2, LiH, H4).
• Employed a range of correlation-consistent basis sets.
• Compared DFT results with full configuration interaction (FCI) and coupled cluster (CCSD) methods.

Main Results:

• SVWN5 functional showed the poorest performance.
• OPTX exchange functional outperformed Becke exchange.
• Hybrid functionals, particularly O3P86, were among the best performers.
• B3LYP was outperformed by O3LYP and yielded some of the least accurate densities among hybrids.
• CCSD provided more accurate densities than DFT for LiH, but DFT was better for stretched H4.
• BP86 and PBE unexpectedly improved density description for stretched H2.

Conclusions:

• O3P86 and other hybrid functionals offer superior accuracy for electronic charge density.
• Despite average density performance, functionals like B3LYP can excel in predicting thermodynamic properties.
• The choice of functional impacts accuracy, with implications for computational chemistry applications.