Assessing Computational\nMethods to Calculate the Binding\nEnergies of Dimers of Five-Membered Heterocyclic Molecules

Computational\nelectronic structure methods, including\nab initio\nand density functional theory (DFT), have been assessed in calculating\nthe binding energies of 14 five-membered heterocyclic dimers. The\nconfigurations were generated using classical molecular dynamics before\noptimization at the MP2/aug-cc-pVTZ. Benchmark binding energies are\ncalculated at the CCSD(T)/CBS level of theory. Among the ab initio\nmethods, the DLPNO-CCSD(T)/CBS method has the best performance, reproducing\nCCSD(T)/CBS with a mean absolute deviation (MAD) of 0.17 kcal/mol.\nIn addition, a schematic CCSD(T)/CBS approach perfectly reproduces\nthe canonical CCSD(T)/CBS with a mean absolute error of 0.08 kcal/mol.\nRegarding DFT functionals, it has been found that counterpoise corrections\nhave negligible effects on the accuracy of the functionals. Furthermore,\nincluding the D3 empirical dispersion considerably enhances the accuracy\nof the DFT functionals. As a result, outstanding performance is noted\nfor the double hybrid functional B2K-PLYP, with a mean absolute error\nof 0.25 kcal/mol. In addition to the B2K-PLYP double hybrid functional,\nM05-D3, B97D, M05-2X-D3, M05-2X, M06-HF, M08-HX, M11, TPSSh-D3, and\nRSX-0DH-D3(BJ) have MAD values lower than 0.5 kcal/mol. These functionals\nare recommended for further investigations of five-membered heterocyclic\nclusters.