NMR chemical shift calculations within local correlation methods: the GIAO-LMP2 approach

A scheme for the calculation of NMR chemical shifts using local second-order Moller-Plesset (LMP2) perturbation theory together with gauge-including atomic orbitals (GIAOs) is presented. Test calculations on the basis of a preliminary implementation within a conventional GIAO-MP2 code show that the deviations between GIAO-LMP2 and GIAO-MP2 are small, e.g., for C-13 typically less than 1 ppm, and that the GIAO-LMP2 approach holds great promise for application to larger molecules.