Self-consistent implementation of a nonlocal van der Waals density functional with a Gaussian basis set

Area of Science:

• Computational chemistry
• Materials science
• Quantum mechanics

Background:

• Common density functional approximations inadequately describe dispersion interactions in van der Waals complexes.
• Empirical corrections offer limited solutions and may lack reliability for diverse systems.
• The first-principles nonlocal van der Waals density functional (vdW-DF) provides a seamless description of dispersion interactions with correct asymptotics.

Purpose of the Study:

• To develop a self-consistent implementation of the vdW-DF using Gaussian basis functions.
• To derive and code the gradients for efficient geometry optimizations.
• To evaluate the performance of vdW-DF with various exchange approximations and assess sensitivity to basis sets and numerical grids.

Main Methods:

• Self-consistent implementation of vdW-DF with Gaussian basis functions.
• Derivation and coding of energy gradients for geometry optimization.
• Testing vdW-DF correlation with multiple exchange approximations and analyzing basis set/grid sensitivity.

Main Results:

• Successful implementation of vdW-DF with Gaussian basis functions and gradients.
• Accurate description of dispersion interactions for weakly interacting systems.
• Nonlocal vdW-DF correlation is robust to grid size, while semilocal exchange requires fine grids for accuracy.
• Pairing vdW-DF with Hartree-Fock exchange leads to significant overbinding.

Conclusions:

• The developed method provides an efficient and accurate approach for studying van der Waals interactions.
• The findings highlight the importance of appropriate exchange functional pairing with vdW-DF.
• The implementation facilitates reliable geometry optimizations and electronic structure calculations for systems dominated by dispersion forces.