A System-Dependent Density-Based Dispersion Correction.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density functional approximations (DFAs) often fail to accurately describe weak molecular interactions due to small electron density overlaps.
• Accurate modeling of these interactions is crucial for understanding chemical bonding, reaction mechanisms, and material properties.

Purpose of the Study:

• To introduce a novel density-dependent dispersion correction (dDXDM) to enhance the accuracy of DFAs for weak molecular interactions.
• To evaluate the performance of the dDXDM correction when combined with popular density functional methods.

Main Methods:

• The dDXDM correction is an a posteriori energy term added to existing DFAs, applicable to all elements.
• Dispersion coefficients are calculated using the exchange-hole dipole moment (XDM) formalism, incorporating density and oxidation state.
• Long-range potentials are supplemented with higher-order terms and a damping factor dependent on Hirshfeld populations and ionization energies.

Main Results:

• The dDXDM correction significantly reduces errors in popular density functionals for both inter- and intramolecular interactions.
• Tested on 145 systems, functionals like PBE-dDXDM, PBE0-dDXDM, and B3LYP-dDXDM achieved mean absolute deviations (MADs) of 0.74-0.84 kcal mol(-1).
• These dDXDM-corrected functionals outperform computationally intensive methods like M06-2X and B2PLYP-D.

Conclusions:

• The dDXDM correction offers a computationally efficient and broadly applicable method to improve the description of weak interactions in DFAs.
• This approach leads to superior accuracy compared to existing dispersion-corrected functionals and some advanced methods.