Delocalized Currents without a Ring of Bonded Atoms: Strong Delocalized Electron Currents Induced by Magnetic Fields in Noncyclic Molecules

Some noncyclic small molecules, electrically neutral or charged, sustain
interatomic electronic currents in the presence of a stationary, spatially uniform magnetic
field. The existence of fairly large delocalized electron flow is demonstrated in H2O, BH3,
NH3, CH4, CH3−CH3, H3O+, CH3+, and NH4
+, by plots of quantum mechanical current
density. Convincing quantitative evidence is arrived at by current strengths, defined via a flux
integral of the ab initio current density. Application of a simple ring current model shows
that the delocalized current strengths account for the out-of-plane component of the
magnetic shielding tensor along the symmetry axis. A definition of delocalized electron
current as a current flowing along a closed loop containing three or more atoms is discussed.