Response properties of AgCl and AgBr under an external static electric field: A density functional study

Density functional theory has been applied to investigate the effect of electric field on the electronic properties of AgCl and AgBr crystals using a static electric field perturbation. A reduction in the band gap value and widening of the band widths are observed with increase in the macroscopic field value indicating a considerable red shift in the absorption spectrum of AgCl and AgBr in the presence of an external electric field. Further, dielectric properties and lattice vibrations at the gamma point are calculated with three different functionals using the CPKS and the Berry phase approach as implemented in CRYSTAL09 code. Finally, the breakdown strength of AgCl and AgBr crystal is evaluated using Callen’s equation. In contrast to the case of alkali halides, it is found that the inclusion of the numerically calculated effective mass ratio into the Callen’s equation considerably improves the agreement between the calculated dielectric strength and the available experimental datum.

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► Calculation of the effect of electric field on the electronic properties of AgCl and AgBr.
► Optical behavior of AgCl and AgBr in the presence of electric field.
► Dielectric constants through CPKS scheme and a berry phase approach.
► Dielectric breakdown strength of AgCl and AgBr through a novel method.
► Comparison of the performance of Callen’s equation in Silver halides and alkali halides.