Theoretical Studies of Glasses

0081006 Drabold该基金支持职业生涯中期PI的工作，对硫属玻璃电子特性的理论研究感兴趣。 这些是玻璃，其中涉及硒和硫，在其纯形式和合金涉及他们。 有三个研究项目：在第一个，有一个计算的电子状态附近的光学间隙，包括晶格动力学效应和使用最先进的方法。 这些状态在这些材料的输运、掺杂和光学特性中至关重要。 第二个项目研究光引起的结构变化。 实验表明，这种光诱导的结构变化可能是空间非局域的，并导致戏剧性的现象，如无热光熔化和巨大的光膨胀。将有一个研究模型的这些玻璃，使用激活松弛技术的Mousseau和Barkema，结合快速，近似从头算方法。 一个有限的研究选定的玻璃的表面状态将进行，既为他们的根本利益，以及光诱导的结构变化，特别是光熔。 最后，还有相关的方法论方面，e。G.非绝热动力学 这些研究将涉及到从最简单的经验势到具有广义梯度修正的局域自旋密度近似中的密度泛函方法等技术的明智应用。这项资助支持了一位职业生涯中期的PI的工作，他对硫属玻璃中的照相效果很感兴趣。 该主题是理解太阳能电池工作效率的关键，因为如果它们是材料中的实质性结构变化，作为光电器件的结果，那么了解这种变化是如何发生的，可能会提出提高电池寿命的方法。 此外，这一主题具有根本的重要性，因为所涉及的物理学是微妙的，其影响已经超出了传统方法和近似的范围。

0081006DraboldThis grant supports the work of a mid-career PI, interested in a theoretical study of the electronic properties of chalcogenide glasses. These are glasses, which involve selenium and sulfur, in their pure form and also alloys involving them. There are three research projects: In the first one, there is a calculation of the electron states near the optical gap, including lattice dynamics effects and using state of the art methods. These states are of critical importance in the transport, doping and optical characteristics of these materials. The second project studies light induced structural changes. Experiments show that such light induced structural changes may be spatially non-local and lead to dramatic phenomena such as athermal photo-melting and giant photo-expansion. There will be a study of models of these glasses, using the activation-relaxation technique of Mousseau and Barkema, in conjunction with fast, approximate ab initio methods. A limited study of the surface states of selected glasses will be performed, both for their fundamental interest as well as for light-induced structural changes, especially photomelting. Finally, there are the associated methodological aspects, e. g. non-adiabatic dynamics. These studies will involve a judicious application of techniques ranging from the simplest empirical potentials to density functional methods in the local spin density approximations with generalized gradient corrections.%%%This grant supports the work of a mid-career PI who is intrigued by the photomechanical effects in chalcogenide glasses. The subject is key to an understanding of the solar cells' operating efficiency in that if their are substantial structural changes in the material, as a result of its operation as a photoelectric device, then an understanding of how that happens might suggest ways of improving the battery lifetimes. Additionally the subject is of fundamental importance since the physics involved is subtle and the effects have been beyond the reach of conventional methods and approximations.***