The effect of intramolecular charge transfer on the diamagnetic susceptibility in some diatomics and small molecules

Abstract

It is shown that molecular second moments and diamagnetic susceptibilities are satisfactorily accounted for by very simple formulae based on the point charge approximation corrected by an additive term which allows for the spatial extension of atomic orbitals. Thus, in spite of the fact that diamagnetic susceptibility is a bulk property, it is expressed as a sum of atomic terms. The effect of the intramolecular charge transfer is of some importance in highly polar compounds. The neutral atom approach is sufficient otherwise. The calculated second moments are reliable enough to serve as a useful check on experimental data. Our results indicate that the experimental values for FClCO and PF₃ are probably in error. The estimated second moments can also be employed as a necessary but not sufficient condition for the balance of the basis set functions in quantum chemical calculations. Namely, it is found that the molecular second moments are highly insensitive to the finer details of the electronic charge distributions in molecules. Therefore, they may not be used as a quantitative test of computed wavefunctions. The same conclusion, although to a lesser extent, holds for diamagnetic susceptibilities.

Additional information

Notes on contributors

N. Mikac

Also at the Faculty of Natural Sciences, University of Zagreb, Department of Physical Chemistry, Marulićev trg 19, 41000 Zagreb, Yugoslavia.