First-principles study on dielectric properties of NaCl crystal and ultrathin NaCl films under finite external electric field

TL;DR

This study uses first-principles calculations to analyze how the dielectric properties of NaCl crystals and ultrathin films respond to external electric fields, highlighting size and surface effects.

Contribution

It provides new insights into the dielectric behavior of ultrathin NaCl films under electric fields, emphasizing the difference between static and high-frequency dielectric constants.

Findings

High-frequency dielectric constant is unaffected by film thickness.

Static dielectric constant varies with film thickness due to surface effects.

Surface atomic configurations influence dielectric response.

Abstract

We present a first-principles study on the dielectric properties of an NaCl crystal and ultrathin NaCl films under a finite external electric field. Our results show that the high-frequency dielectric constant of the films is not affected by the finite size effect from crystal surfaces and is close to that of the crystal, whereas the static one is sensitive to the thickness of the film due to the difference in the atomic configurations between the surface and inside of the film.