Band electron spectrum and optical properties of KDP-crystals under the external hydrostatic pressure

摘要

The electron spectrum of the KDP-type crystals has been investigated as audfunction of the external hydrostatic pressure using the tight-binding approximation.udThe joint density of electron states, real and imaginary parts of theuddielectric permeability, refraction indices, the gyration coefficient, absorptionudand reflection coefficients for different polarizations of light are determined.udTheir pressure and frequency dependencies are investigated. Theudresults are discussed by comparing them with the experimental data onudpiezooptic coefficients. The anomalous behaviour of the optical constantsudat the pressure p ~≃ 17 kbar is due to the transformation of the hydrogenudbond potential from a double minimum one to a single minimum one, whereudthe proton is localised at the midpoint of the hydrogen bond.