Hybrid density functional study of electronic and optical properties of phase change memory material: $\mathrm{Ge_{2}Sb_{2}Te_{5}}$

摘要

In this article, we use hybrid density functional (HSE06) to study thecrystal and electronic structures and optical properties of well known phasechange memory material $\mathrm{Ge_{2}Sb_{2}Te_{5}}$. We calculate thestructural parameters, band gaps and dielectric functions of three stablestructures of this material. We also analyze the electron charge distributionusing the Bader's theory of charge analysis. We find that hybrid densityfunctional slightly overestimate the value of 'C' parameter. However, overall,our results calculated with the use of hybrid density functional (HSE06) arevery close to available experimental values than calculated with the use of PBEfunctional. Specifically, the electronic band gap values of this materialcalculated with HSE06 are in good agreement with the available experimentaldata in the literature. Furthermore, we perform the charge analysis and findthat naive ionic model fails to explain the charge distribution between theconstituent atoms, showing the complex nature of this compound.