MAGNETIC DIPOLE AND ELECTRIC QUADRUPOLE INTERACTIONS IN THE THEORY OFFIRST-ORDER SPATIAL-DISPERSION PHENOMENA

The theory of the molecular optical response in the first-order spatia l dispersion approximation is developed. It is shown that in the absen ce of a DC electric and/or magnetic field the electric quadrupole and magnetic dipole interactions are inseparable on the microscopic level. The equations for first-, second- and third-order hyperpolarizabiliti es, which are responsible for such polarization phenomena as natural a nd light-induced polarization plane rotation and quadrupole second har monic generation are obtained.