THE USE OF LOCALLY DENSE BASIS-SETS IN CORRELATED NMR CHEMICAL SHIELDING CALCULATIONS

Locally dense basis sets employ large sets of functions on a particula r atom or small molecular region, and smaller or attenuated sets elsew here. This approach has been shown to be very useful in calculating NM R chemical shieldings at the Hartree-Fock level on systems otherwise c omputationally expensive. In the present work it is shown that such mi xed basis sets can also be successfully employed at the second order m any-body perturbation theory level (MBPT[2], or MP2). Shielding calcul ations have been carried out on a variety of carbon-, nitrogen-, oxyge n-, and phosphorus-containing molecules and the locally dense shieldin g results analyzed at Hartree-Fock and MP2 levels, and with our recent ly introduced estimated infinite order Moller-Plesset (EMPI) approach.