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ISSN 2071-0194   Ukr. J. Phys. 2015, Vol. 60, N 6, p.528-537
doi:10.15407/ujpe60.06.0528   Paper

Stupka A.A.

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

Long-Wave Optical Vibrations in Diatomic Ionic Crystals

Section: Solid matter
Language: English

Abstract: Long-wave phonon-polaritons and longitudinal optical phonons have been considered as eigenwaves of the electromagnetic field in ionic crystals with two atoms per unit cell. The Kun Huang model is used to describe the sublattices of point charges vibrating with the frequency ω0. The dispersion laws for optical vibrations in crystals are generalized, by considering the thermal motion of charges. An additional longitudinal phonon with the frequency 2ω0 and two upper phonon-polaritons are found in the second-order approximation with respect to the ratio between the standard deviation and the wavelength.

Key words: ionic crystal, electromagnetic field; long-wave vibrations, phonon-polaritons, longitudinal optical phonons, harmonics.