Coupled-Hartree-Fock calculations of susceptibilities and magnetic shielding constants

Coupled Hartree-Fock calculations on the susceptibilities X and magnetic shielding constants σ are reported for the title molecules. Very large gaussian basis sets have been used in order to come sufficiently close to the Hartree-Fock limit. The basis set dependence of X and σ is discussed. In addition the applicability of two methods (maximum of X [20] and closure relations [21, 22]) for the prediction of the best gauge origins is investigated. For C2H2, C2H4 aand C2H6 accurate theoretical results for the complete tensors of X and σ are given for the first time. For ethylene antishielding of σ yy C is observed and illustrated by means of the induced electric currents.