Abstract
With the calculation of the two independent components of the dipoleoctupole polarizability tensor (E) of H2 + we complete our knowledge of all polarizability tensors of this ion up to fourth-rank. These tensors may be directly used to investigate the effect of a distant charge on the isolated nuclear-fixed molecule. On the other hand, if the molecule is rotating then orientationally-averaged values (which include vibrational and rotational contributions) must be used and these are tabulated here for the lowest eleven rotational states for the ground vibrational state of H2 +. Attention is drawn to the fact that these two situations lead to equations which are both qualitatively and quantitatively different.