Electronic structure of polymers for photovoltaic applications and strongly correlated electron systems

这项研究计划提出使用电子结构方法来计算新材料的性质。这一提议主要有两个主题：第一个是用于光伏的聚合物，另一个是强相关的电子材料，如高T_c和新发现的铁化合物。通过方法开发，我们打算更好地描述这些材料的性质，以便计算在帮助实验工作方面更有用。 对于用于光伏应用的聚合物，具体目标是能够准确计算建议聚合物的光谱，以便评估是否应该进行合成。这将通过改进GW方法来实现，以便能够将其应用于聚合体系。我们还将能够直接计算电离势和电子亲和势，这将有助于设计器件的最佳组合。我们的最终目标将是提出能够帮助我们达到10%电力转换效率的聚合物，以便有机太阳能电池能够成为目前更昂贵技术的真正替代品。 对于强关联的电子材料，目标是开发包含更多关联的泛函。这些改进将通过计算声子性质来测试，以将它们与现有的实验数据进行比较。另一个测试将是将实验测量的de Haas-van Alphen频率与计算的频率进行比较，计算的频率可以从计算的费米面的形态获得。

This research program proposes the use of electronic structure methods to calculate the properties of novel materials. There are two main topics to this proposal: the first is polymers for photovoltaic applications and the other is strongly correlated electron materials such as the high-Tc and the newly discovered iron pnictides. Through method developments, we intend to better describe the properties of these materials such that calculations can be more useful in assisting experimental efforts. For polymers used in photovoltaic applications, the specific goals are to be able to accurately calculate the optical spectrum of proposed polymers in order to evaluate if their synthesis should be pursued. This will be done by improving the GW method to be able to apply it to polymeric systems. We will also be able to directly calculate the ionization potential and the electron affinity which will help to design the best combination in devices. Our ultimate goal will be to propose polymers that can help us reach 10% power conversion efficiency so that organic solar cells can be a real alternative to the present more expensive technology. For the strongly correlated electron materials, the goal is to develop functionals that include more correlations. These improvements will be tested by calculating the phonon properties to compare them to existing experimental data. Another test will be the comparison of experimentally measured de Haas-van Alphen frequencies with calculated ones which can be obtained from the morphology of the Fermi surface calculated.