Japan JSPS Program: First-principles Investigation of Quantum Diffusion in Alkali Halides

9602520 Briere该奖项支持日本科学促进会为Tina Marie Briere博士在日本东京大学固态物理研究所提供的为期12个月的博士后奖学金。Briere博士将与该研究所教授Shinsi Tsuneyuki博士合作开展一项名为“碱金属中量子扩散的第一性原理研究”的研究项目。这项拟议的研究将利用理论第一性原理技术来研究Mu在碱金属卤化物中的量子扩散。最近使用Muon自旋弛豫的实验已经绘制了扩散速率随温度的函数图。在高温区和低温区的扩散速率曲线有很大的不同，表明了两种不同类型的扩散：非相干量子扩散和相干量子扩散。这项研究的目的是从理论的角度描述低温区的扩散速率，其基础不依赖于实验参数。Muonium(Mu)是一种由一个Muon和一个电子组成的轻原子，之所以被选为分析对象，是因为它的轻质量允许对量子扩散进行清晰的实验观察。Car-Parinello第一原理方法将被用来绘制Mu原子在KCl晶体中扩散时的势能面。然后用数值方法确定Mu的波函数，然后计算扩散参数，然后可以将这些参数与早期的实验进行比较(例如，Mu扩散速率)。***

9602520 Briere This award supports a 12 month Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowship for Dr. Tina Marie Briere at the Institute of Solid State Physics, University of Tokyo in Tokyo, Japan. Dr. Briere will work with Dr. Shinji Tsuneyuki, professor at the Institute, on a research project entitled "First-principles Investigation of Quantum Diffusion in Alkali Halides". The proposed research will utilize theoretical first- principles techniques in order to study quantum diffusion of muonium in alkali halides. Recent experiments using muon spin relaxation have mapped the diffusion rate as a function of temperature. The curve of the diffusion rate is quite different in the high and low temperature regions, indicating two different types of diffusion: incoherent and coherent quantum. The goal of the proposed research is to describe the diffusion rate in the low-temperature region from a theoretical viewpoint whose basis does not depend on experimental parameters. Muonium (Mu), a light atom consisting of a muon and an electron, has been chosen for the analysis because its light mass has allowed for clear experimental observation of quantum diffusion. The Car- Parinello first-principles method will be used to map the potential energy surface as the muonium atom diffuses through a KCl crystal. The wavefunction of Mu will then be determined numerically, followed by calculation of diffusion parameters which can then be compared to earlier experiments (e.g. Mu diffusion rate). ***