CALCULATION OF MAGNETIC-PROPERTIES - VII - ELECTRON-CORRELATED MAGNETIZABILITY POLARIZABILITIES AND NUCLEAR SHIELDING POLARIZABILITIES FOR 9 SMALL MOLECULES

The effects of a static uniform electric held on the NMR shielding and magnetizability of F-2, HCN, HNC, HCCH, H2O, NH3, CH4, HCHO, and H2O2 are investigated. The quantities which govern these effects are the s hielding and magnetizability polarizabilities and these are calculated in a mixed numerical-analytical scheme at both the electron-uncorrela ted and electron-correlated levels of theory. For the latter, correlat ion is introduced via second-or third-order Moller-Plesset theory or v ia linearized coupled cluster double excitation theory. This is the fi rst time that these theories have been applied to these properties for these molecules. Furthermore, for F-2, HNC, and H2O2 there have been no calculations of any kind before, and for NH3 and HCHO there have be en no correlated calculations, for HCHO the magnetizability polarizabi lity has not been determined previously. The investigation highlights the extreme difficulty, in most cases, of obtaining definitive values for these properties; this is especially true for F-2 where electron c orrelation plays a dominant role. In general, electron correlation is much more important for the rotationally averaged shielding polarizabi lities than for the magnetizability-polarizability anisotropy which go verns the Cotton-Mouton effect.