The study of performance of DFT functional for van der Waals interactions

In the present study, the performance of different exchange–correlation functional of DFT for van der Waals molecules has been studied by optimising the structures with augmented cc-pVTZ basis sets. The structural parameters along with vibrational frequencies and rotational constants were calculated using 15 different exchange–correlations functional for 10 molecules and compared with experimental results. Further the interaction energies (basis set superposition error corrected) were calculated using different DFT exchange–correlation functional and compared with MP2 and CCSD(T) method. The error analysis was carried out using MUE (mean unsigned error) and MAPE (mean absolute percentage error) statistical methods.