Extension of the D3 dispersion coefficient model.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Accurate computation of molecular dipole-dipole dispersion coefficients is crucial for understanding non-covalent interactions.
• Existing methods like the D3 scheme provide a foundation but can be improved in accuracy and efficiency.

Purpose of the Study:

• To introduce a novel, efficient computational model named D4 for calculating molecular dipole-dipole dispersion coefficients.
• To enhance the accuracy of dispersion coefficient calculations by incorporating electronic density information.

Main Methods:

• The D4 model calculates dispersion coefficients as sums of atom-in-molecule coefficients over atom pairs.
• It utilizes dynamic polarizabilities from time-dependent density functional theory (TD-DFT) and incorporates atomic partial charges from semi-empirical quantum mechanics to scale polarizabilities.
• Casimir-Polder integration is employed for on-the-fly calculation of coefficients.

Main Results:

• The D4 method demonstrates significantly lower errors in dispersion coefficients compared to the D3 scheme and other computationally intensive methods.
• It achieves high accuracy and efficiency in calculating isotropic, charge, and hybridization-dependent static polarizabilities.
• Damping function parameters are provided for TPSS, PBE0, and B3LYP density functionals.

Conclusions:

• The D4 model offers a substantial improvement in the accuracy and efficiency of calculating molecular dispersion coefficients.
• This advancement is valuable for accurate modeling of non-covalent interactions in various chemical systems.
• The model provides a robust tool for computational chemistry research and applications.