화학공학소재연구정보센터
International Journal of Molecular Sciences, Vol.4, No.3, 143-157, 2003
The spin-spin coupling constants in ethane, methanol and methylamine: A comparison of DFT, MCSCF and CCSD results
The spin-spin coupling constants in ethane, methylamine, and methanol have been calculated using density-functional theory (DFT), coupled-cluster singles-and-doubles (CCSD) theory, and multiconfigurational self-consistent field (MCSCF) theory so as to benchmark the performance of DFT against high-level ab initio methods and experimental data. For each molecule, the Karplus curve has been evaluated at the three computational levels. The comparisons with ab initio methods indicate that DFT reproduces the (1)J(CH), (1)J(CC), and (1)J(NH) one-bond couplings well but is less accurate for (1)J(CN), (1)J(OH), and (1)J(CO). While DFT performs well for the geminal couplings (2)J(HH) and (2)J(CH), it tends to overestimate the vicinal (3)J(HH) couplings slightly although it is sufficiently accurate for most purposes.