Dispersion-Corrected DFT Struggles with Predicting Three-Body Interaction Energies.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density functional theory (DFT) is a widely used method for electronic structure calculations.
• Dispersion-corrected DFT (DFT-D) methods aim to improve accuracy by including empirical dispersion corrections.
• Accurate calculation of many-body interactions is crucial for understanding intermolecular forces and material properties.

Purpose of the Study:

• To evaluate the accuracy of DFT-D schemes, including the many-body dispersion (MBD) method, for predicting three-body interaction energies.
• To identify the limitations of current DFT-D approaches in capturing non-dispersion related deficiencies.
• To propose an improved method for accurate calculation of three-body interaction energies.

Main Methods:

• Assessment of standard DFT-D schemes and the MBD method for calculating three-body interaction energies.
• Analysis of the sources of inaccuracy in DFT-D methods, particularly concerning non-dispersion terms.
• Development and testing of an adjusted MBD approach in conjunction with supermolecular MP2 calculations.

Main Results:

• DFT-D schemes, including MBD, demonstrate limitations in accurately predicting three-body interaction energies.
• Inaccuracies stem from inherent deficiencies in standard DFT functionals, not solely from dispersion components.
• The proposed adjustment to the MBD approach achieves good accuracy for three-body interaction energies when combined with MP2.

Conclusions:

• Current DFT-D methods, including MBD, are insufficient for reliable prediction of three-body interaction energies.
• Addressing internal DFT functional deficiencies is key to improving many-body interaction calculations.
• The adjusted MBD method offers a promising avenue for accurate three-body energy calculations, especially when paired with MP2.