Electronic Structure of Ge-Sb-Te System Calculated by DV-Xα Method

Abstract

Germanium-antimony-tellurium (Ge-Sb-Te) system comprised the GeSb₂Te₄, GeSb₄Te₇, and Ge₂Sb₂Te₅ compounds which are the most widely used materials with electronic structure of narrow band gap energy. In this work, we studied electronic structure of Ge-Sb-Te system by using the discrete variational (DV)-Xα molecular orbital method based on the self-consistent Hartree-Fock-Slater model in order to investigate thermoelectric materials. The calculation was designed based on Ge₁₃Sb₂₀Te₅₂, Ge₇Sb₁₂Te₄₀, and Ge₁₄Sb₆Te₂₆ model cluster atoms which performed to GeSb₂Te₄, Ge₂Sb₂Te₅, and GeSb₄Te₇ compounds with the symmetry (9Cv) in order to convert radial function for molecular orbitals of model cluster atoms. The findings were the electronic structure comprising the model cluster atoms, energy level, density of state, bond overlap population and electron density at wave function number of HOMO and LUMO showed narrow energy gap of 0.022 eV, 0.016 eV and 0.037 eV of Ge₁₃Sb₂₆Te₅₂, Ge₇Sb₁₂Te₄₀, and Ge₁₄Sb₆Te₂₆, respectively. The narrow energy gap was relevant to improving the thermoelectric performance of Ge-Sb-Te system.

Keywords:

• Electronic structure
• Ge-Sb-Te system
• DV-Xα molecular orbital method