Ab initio determination of ion-traps in silver-doped chalcogenide glass

Direct ab initio MD simulation of silver ion diffusion in chalcogenide glasses

In this paper, we present new models of germanium selenide chalcogenide glasses heavily doped with silver. The models were readily obtained with ab initio molecular dynamics and their structure agrees closely with diffraction measurements. Thermal molecular dynamics simulation reveals the dynamics of Ag+ ions and the existence of trapping centers as conjectured in other theory work. We show that first principles simulation is a powerful tool to reveal the motion of ions in glass.

{\it Ab initio} Simulation of Silver Transport in Ge_xSe_1-x: Ag

In this paper, we present models of Ge-Se glasses heavily doped with Ag obtained from {\it ab initio} simulation and study the dynamics of the network with an emphasis on the motion of Ag$^+$ ions. The models are analyzed with partial pair correlation functions, static structure factors and novel wavelet techniques. The electronic properties are characterized by the electronic density of states and analysis of specific electronic eigenstates. As Ag content increases, the optical band gap increases. Ag diffusion is observed directly from thermal simulation. The most diffusive Ag$^+$ ions move p…

Atomistic Simulations of Flash Memory Materials Based on Chalcogenide Glasses

In this chapter, by using ab-initio molecular dynamics, we introduce the latest simulation results on two materials for flash memory devices: Ge2Sb2Te5 and Ge-Se-Cu-Ag. This chapter is a review of our previous work including some of our published figures and text in Cai et al. (2010) and Prasai & Drabold (2011) and also includes several new results.

热流正则化下机器学习原子间势的构建及其在银硫族化合物功率谱分析中的应用

Construction of Machine-Learning Interatomic Potential Under Heat Flux Regularization and Its Application to Power Spectrum Analysis for Silver Chalcogenides

提出一种基于热流正则化的机器学习原子间势构建方法，通过在代价函数中引入热流正则化项消除非物理热流，并在银硫族化合物中验证了其能准确分析热流功率谱并提升模型鲁棒性。

Coexistence of tetrahedral and octahedral-like sites in amorphous phase change materials

Chalcogenide alloys are materials of interest for optical recording and non-volatile memories. We perform ab-initio molecular dynamics simulations aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the prototypical material in this class. First principles simulations show that amorphous GST obtained by quenching from the liquid phase displays two types of short range order. One third of Ge atoms are in a tetrahedral environment while the remaining Ge, Sb and Te atoms display a defective octahedral environment, reminiscent of cubic crystalline GST.

Influence of the cooling-rate on the glass transition temperature and the structural properties of glassy GeS2: an ab initio molecular dynamics study

Using density-functional molecular dynamics simulations we analyzed the cooling-rate effects on the physical properties of GeS$_2$ chalcogenide glasses. Liquid samples were cooled linearly in time according to $T(t) = T_0 - γt$ where $γ$ is the cooling rate. We found that our model leads to a promising description of the glass transition temperature $T_g$ as a function of $γ$ and gives a correct $T_g$ for experimental cooling rates. We also investigated the dependence of the structural properties on the cooling rate. We show that, globally, the properties determined from our simulations are in…