Effects of the higher electron correlation correction on the calculated intermolecular interaction energies of benzene and naphthalene dimers: comparision between MP2 and CCSD(T) calculations

摘要

Intermolecular interaction energies of parallel and T-shape benzene dimers and parallel naphthalene dimer were calcualted with MP2,MP3,MP4(SDQ), MP4(SDTQ), CCSD and CCSD(T) electron correlation corrections usign several basis sets. The MP2 calculations considerably overestimated the attraction compared to teh CCSD(T) ones. The MP2 correlation interaction energies, the differences between the HF and MP2 interaction energies, were 21-38% larger than the corresponding CCSD(T) ones. The MP4(SDQ) and CCSD calculations substantially underestimated the attraction compared to MP4(SDTQ) and CCSD(T), which indicated the importance of triple excitation. The estimated CCSD(T) interaction energies of the three dimers with reasonably large basis sets were -1.74,-2.50 and -5.69 kcal/mol, respectively.