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Current issue   Ukr. J. Phys. 2015, Vol. 59, N 8, p.793-796
doi:10.15407/ujpe59.08.0793    Paper

Stupka A.A.

Oles Honchar Dnipropetrovsk National University
(72, Gagarin Ave., Dnipropetrovsk 49050, Ukraine; e-mail: antonstupka@mail.ru)

Frequencies of Long-Wave Phonon-Polaritons and Optical Phonons in Diatomic Ionic Crystals

Section: Solid matter
Original Author's Text: Ukrainian

Abstract: Long-wave phonon-polaritons and longitudinal optical phonons in ionic crystals with two atoms per unit cell have been considered. The model of the point charge and the self-consistent electromagnetic field in the dielectric medium is used. The standard dispersion laws for both branches of phonon-polaritons regarded as transversal waves are obtained. The frequency of longitudinal optical phonons is expressed in terms of the ion plasma frequency in an insulator multiplied by the factor √ε00, where ε0 is the static dielectric constant, and ε is the high-frequency one. A good agreement between the found expression and tabulated data is found.

Key words: ionic crystal, self-consistent electromagnetic field, long-wave vibrations, phononpolaritons, longitudinal optical phonons, ion plasma frequency.