Where Does the Density Localize? Convergent Behavior for Global Hybrids, Range Separation, and DFT+U.

Area of Science:

• Computational chemistry
• Quantum chemistry

Background:

• Approximate density functional theory (DFT) methods often exhibit self-interaction error, leading to delocalization errors in calculated properties.
• While corrections for energetic delocalization errors are established, their impact on electron density remains less explored.

Purpose of the Study:

• To investigate and compare the effects of different DFT correction methods on electron density delocalization.
• To assess the influence of these corrections on partial charges and magnetic moments in transition metal complexes.

Main Methods:

• Comparison of DFT+U, global hybrid, and range-separated hybrid tuning methods.
• Analysis of ground state densities for 32 transition metal complexes with varying properties.
• Validation against accurate wave function theory references.

Main Results:

• All tested correction methods (DFT+U, global hybrid, range-separated hybrid) showed qualitatively similar effects on ground state densities.
• Consistent observation of substantial metal charge loss and ligand charge gain across diverse systems and methods.
• Charge loss preferentially occurred from minority spin, increasing the magnetic moment.

Conclusions:

• Correction methods for energetic delocalization errors have significant, consistent impacts on electron density, including charge redistribution and magnetic moment changes.
• Optimal tuning parameters for correcting density delocalization and associated errors in partial charges and magnetic moments differ from those for energetic errors.
• Development of multifaceted DFT error correction strategies is needed to address both density and energetic delocalization errors separately.