The structural, vibrational and electronic properties of several compositions of amorphous Ge-Se-Te are studied from a combination of x-ray diffraction and density functional-based molecular dynamics. Different structural properties are considered such as structure factors, pair distribution functions, angular distributions, coordination numbers, and neighbor distributions. We compare results with experimental findings and a satisfying agreement is found for the structure functions in real and reciprocal spaces. The short range order is found to be more complex than in related binaries that result in mixed geometries ($\simeq 65\%–75\%$ tetrahedral, and remaining defect octahedral) for a dominant fourfold Ge (80%). The chalcogen atoms are dominantly twofold, the former having furthermore an important fraction of threefold coordinated atoms (30%–40%). The obtained model structures indicate that Ge-Ge, Ge-Se, and Ge-Te bonds dominate with small fractions of Te-Te bonds remaining from the base system GeTe. The investigation of electronic properties indicates that the addition of Se atoms will lead to Te-related bands that are much more localized so that Ge-Te-Se can be regarded as having an increased covalent character with respect to GeTe.

中文翻译：

---

通过硒替代改变非晶 GeTe 的结构、电子和振动特性：实验约束的密度泛函研究

结合 X 射线衍射和基于密度泛函的分子动力学，研究了几种非晶 Ge-Se-Te 组合物的结构、振动和电子特性。考虑了不同的结构特性，例如结构因子、对分布函数、角分布、配位数和邻居分布。我们将结果与实验结果进行比较，发现实空间和倒易空间中的结构函数具有令人满意的一致性。发现短程顺序比导致混合几何的相关二进制更复杂（$\simeq 65\%–75\%$四面体和剩余缺陷八面体）占主导地位的四重 Ge（80%）。硫族原子主要是双重的，前者还具有重要的三重配位原子 (30%–40%)。获得的模型结构表明，Ge-Ge、Ge-Se 和 Ge-Te 键占主导地位，而小部分 Te-Te 键仍保留在基础系统 GeTe 中。电子特性的研究表明，Se 原子的添加将导致更局域化的 Te 相关带，因此可以认为 Ge-Te-Se 相对于 GeTe 具有增加的共价特性。