Development of electronic structure methods for novel applications

一开始，物理学的研究要么是实验性的，要么是理论性的。随着高性能计算的出现，第三种方法现在提供给我们，可以帮助实验和理论工作。本课题以电子结构方法在新型材料研究中的应用与发展为主题。采用的主要研究工具是基于密度泛函理论（DFT）的计算方法、GW方法和基于动态平均场理论的相关方法。由于不需要外部参数，这些第一性原理技术允许对所研究系统的电子和结构特性进行预测。这些方法正在不断发展，以扩大其适用范围。目标是准确地描述以前没有使用这些方法的系统的属性。我将描述在这个研究计划的过程中将要研究的几个项目，我将指出每个案例中的挑战。我的研究小组的主要重点之一是电子-声子耦合的精确计算。特别是，现在已知密度泛函理论本身不足以描述大多数相关系统的电子性质。动力学平均场理论（DMFT）等方法对于处理这些系统的电子结构是必要的。这些方法对电子-声子耦合的影响尚未得到充分的研究。为了评估DMFT方法对电子-声子耦合的影响，我们将考虑它是否可以解释在高tc电子色散中观察到的扭结结构。另一个更好的处理可能有助于解释的性质是在计算de Haas - van Alphen实验的量子振荡中获得的有效质量。在我的研究活动中，另一个目前感兴趣的话题是能源，更具体地说，是利用电池储存能量。我们将考虑使用有机材料的电池系统，这些材料的特定应用潜力尚未得到充分探索。最后，我们将继续我们正在进行的纳米材料，如石墨烯和碳纳米管的研究。更具体地说，通过与我们的实验伙伴合作，他们展示了合成磷烯的能力，我们打算研究这种系统的电子特性，以帮助这项技术的发展及其未来的应用。在这个项目结束时，我们将开发出更好的工具来理解材料科学，这将有助于我们的发现过程。

In its beginning, research in Physics was either an experimental or a theoretical endeavour. With the advent of High Performance Computing, a third way is now offered to us that can assist both experiment and theory efforts. This research proposal has for main theme the use and development of electronic structure methods to study novel materials. The principal research tools employed are the computational methods based on density functional theory (DFT), the GW approach and the correlated method based on the dynamical mean-field theory. These are first-principle techniques that allow to make predictions of the electronic and structural properties of the systems studied since no external parameters are required. These methods are in continuous development to extend their range of applicabilities. The goal is to describe accurately the properties of systems where these approaches were not used before. I will describe a few projects that will be studied during the course of this research program, and I will point out the challenges in each case.One of the main focus of my research group is the accurate calculations of the electron-phonon coupling. In particular, it is now known that density-functional theory by itself is not sufficient to describe the electronic properties of most correlated systems. Methods such as the dynamical mean-field theory (DMFT) are necessary for the treatment of the electronic structure of these systems. What has not yet been fully examined is the impact of such approaches on the electron-phonon coupling. In order to assess the effect of the DMFT method on the electron-phonon coupling we will consider if it could explain the kink structure observed in the electronic dispersion of the high-Tc. Another property where a better treatment is likely to help in the interpretation is in the calculations of effective masses obtained in the quantum oscillations of the de Haas - van Alphen experiments. Another topic of present interest in my research activities concerns energy, more specifically the storage of energy with the help of batteries. We will consider battery systems that use organic materials which potential for specific applications has not yet been fully explored.Lastly, we will continue our ongoing investigation of nanomaterials like graphene and carbon nanotubes. More specifically, through collaboration with our experimental partners who demonstrated the abilities to synthesize phosphorene, we intend to study the electronic properties of such systems to help in the development of this technology and its future applications.At the end of this project, we will have developed better tools to understand material science which will facilitate our discovery process.