NMR coupling constants with the equation-of-motion coupled-cluster method

The first principal of theoretical prediction of NMR spin-spin coupling constants, has not been satisfactory accomplished. Hartree-Fock self-consistent field results are not of predictive quality, so electron correlation is essential. Unlike NMR chemical shifts, which, for most organic systems, can be adequately described with gauge-including atomic orbitals (GIAO) at the lowest level of correlation, MPBP(2), the sector spin-spin coupling constants seem to require a more complete description of electron correlation. In this talk, we will discuss the use of the equation-of-motion coupled-cluster (EOM-CC) method for the treatment of each properties. We will present results for the recognized difficult molecules, like HF, CH3F, CH3-CN, etc. demonstrating an accuracy of about 10% compound to experiment Using this predictive capability we will address the experimentally unknown coupling constant for bridged Hydrogen and Carbon atoms in some non-classical combinations carbocations