Polar modes in molecular crystals: Ewald splitting of infrared and Raman lines
- 1 December 1984
- journal article
- research article
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 62 (12) , 1237-1247
- https://doi.org/10.1139/p84-168
Abstract
Ewald's long-wave method is applied to long-range electrostatic potentials within the framework of quasi-harmonic lattice dynamics of molecular crystals. The angular dependence of phonon frequencies, transition dipole moments, and polarizabilities of single crystals is derived for all crystallographic species. Analytical expressions for infrared and Raman line shapes in powder samples arc obtained, pointing out the dependence of line shapes on the crystal symmetry and the radiation polarization. The infrared and Raman spectra of polycrystalline HCl are discussed.Keywords
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