Development of electronic structure methods for novel applications

起初，物理学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，现在为我们提供了第三种方法，可以帮助实验和理论工作。 本研究计划的主要主题是电子结构方法的使用和发展，以研究新材料。主要的研究工具是基于密度泛函理论（DFT）的计算方法，GW方法和基于动力学平均场理论的相关方法。这些都是第一原理技术，允许进行研究的系统的电子和结构特性的预测，因为没有外部参数是必需的。这些方法正在不断发展，以扩大其适用范围。我们的目标是准确地描述这些方法以前没有使用过的系统的属性。我将描述在本研究计划期间将研究的几个项目，并指出每种情况下的挑战。 我的研究小组的主要焦点之一是电子-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。尚未得到充分研究的是这种方法对电子-声子耦合的影响。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的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de哈斯-货车阿尔芬实验的量子振荡中获得的有效质量的计算。 在我的研究活动中，目前感兴趣的另一个主题涉及能源，更具体地说，是在电池的帮助下储存能量。我们将考虑使用有机材料的电池系统，其特定应用的潜力尚未得到充分开发。 最后，我们将继续对石墨烯和碳纳米管等纳米材料进行研究。更具体地说，通过与证明了合成磷烯能力的实验合作伙伴合作，我们打算研究此类系统的电子性质，以帮助开发这项技术及其未来应用。 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，这将促进我们的发现过程。

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.