Nonlinear response of the benzene molecule to strong magnetic fields

The fourth-rank hypermagnetizability tensor of the benzene molecule has been evaluated at thecoupled Hartree–Fock level of accuracy within the conventional common-origin approach, adoptinggaugeless basis sets of increasing size and flexibility. The degree of convergence of theoreticaltensor components has been estimated allowing for two different coordinate systems. It is shownthat a strong magnetic field perpendicular to the plane of the molecule causes a distortion of theelectron charge density, which tends to concentrate in the region of the C–C bonds. This chargecontraction has a dynamical origin, and can be interpreted as a feedback effect in terms of theclassical Lorentz force acting on the electron current density.