A lattice-dynamical calculation applicable to crystals of any structural complexity and any symmetry (that permits optical activity) reveals three mechanisms causing optical activity in crystals: electric-dipole–magnetic-dipole interference, electric-dipole–electric-quadrupole interference, and first-order wave-vector dispersion of the bonding forces. Only the last mechanism was found by Born and Huang from lattice dynamics, while quantum-mechanical derivations have produced only the other two. Thus the present derivation removes a discrepancy between these two approaches, which, since they deal with a long-wavelength phenomenon, should produce closely comparable formulas. The first two mechanisms give terms in the rotatory power proportional to ω2/(ωi2 − ω2), whereas the third mechanism gives terms proportional to ω2/(ωi2 − ω2) (ωj2 − ω2). Both types of term have been shown to be necessary to fit frequency dispersion in particular crystals. Thus the present theory produces all the known mechanisms along with the needed dispersion from a general, unified, basic approach.
© 1989 Optical Society of America
Original Manuscript: October 3, 1988
Manuscript Accepted: February 17, 1989
Published: June 1, 1989
D. F. Nelson, "Mechanisms and dispersion of crystalline optical activity," J. Opt. Soc. Am. B 6, 1110-1116 (1989)