Are dispersion corrections accurate outside equilibrium? A case study on benzene

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Quantum chemistry

Background:

• Accurate modeling of dispersion forces is crucial for predicting molecular interactions.
• Modern dispersion models show promise but their reliability outside equilibrium is uncertain.

Purpose of the Study:

• To evaluate the performance of various dispersion models for the benzene dimer.
• To assess the ability of these models to describe potential-energy curves, forces, and energies outside equilibrium.

Main Methods:

• Comparative analysis of dispersion models including exchange-hole dipole moment (XDM), many-body dispersion (MBD), Grimme-D, and van der Waals density functional approximations (vdW-DFAs).
• Benchmarking against reference calculations across several potential-energy curves of the benzene dimer.

Main Results:

• The XDM model demonstrated the highest overall agreement with reference data for energies and forces.
• Many-body dispersion (MBD) and its fractionally ionic (FI) variant performed comparably to XDM.
• Popular methods like Grimme-D and vdW-DFAs showed underperformance.
• The M06-L meta-GGA functional performed well despite lacking explicit dispersion corrections.

Conclusions:

• The XDM model is recommended for describing benzene dimer interactions, especially outside equilibrium.
• MBD and FI-MBD are also reliable alternatives.
• Further investigation is needed for methods like SCAN+rVV10.