Abstract/Summary

Total and three-body interaction energies are calculated for a benchmark set of three-body systems using a range of different types of Density Functional Theory (DFT) methods, with the results compared to CCSD(T)/CBS results from the benchmark reference [Phys. Chem. Chem. Phys. 2023, 25 28621-28637]. Inclusion of HF exchange, either via a global or range-separated hybrid approach, or inclusion of empirical dispersion corrections increases accuracy for total and three-body interactions. Basis set convergence testing shows that the aug-cc-pVTZ basis set is well converged, with little to no change seen when using quadruple-zeta basis sets. The accuracy of the DFT methods is similar when calculating interaction energies for both global and local minimum structures. Overall, the CAM-B3LYP-D3BJ, B97D3, or B97XD functionals are recommended for calculating three-body interactions.