MAGNETIC PROPERTIES OF POLYATOMIC MOLECULES .I. MAGNETIC SUSCEPTIBILITY OF H2O,NH3, CH4, H2O2

The magnetic susceptibility of H2O, NH3, CH 4, and H2O2 molecules has been evaluated by the perturbed HF scheme. Several wavefunctions, all of LCAO SCF MO type, have been considered. By using a double perturbation technique we derive some useful quantities which allow one to evaluate diamagnetic and paramagnetic contributions to the susceptibility for any gauge. The results corresponding to the largest basis sets are in satisfactory agreement with experimental data. The dependence of the evaluated quantities upon the gauge transformation corresponding to a change of the origin of the vector potential has been examined in detail.