Electronic Structure of Pristine and Highly Doped Conducting Polymers

原始和高掺杂导电聚合物的电子结构

• 批准号: 8702148
• 负责人: Miklos Kertesz
• 金额: $ 12.47万
• 依托单位: Georgetown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1991-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8702148&HistoricalAwards=false
• 关键词: Electronic; Structure; Pristine; Highly; Doped

The proposed research is problem oriented: they aim to understand at microscopic level, and thereby gain more control over, the chemical factors which influence the structure and electronic structure of highly doped (well-conducting) and pristine (semiconducting) conjugated polymers. Their low-dimensional nature causes very large electron-proton interactions and nuclear rearrangements, which lie at the core of electron-proton interactions and nuclear rearrangements, which lie at the core of their unusual electrical and optical properties. Since no quantum mechanical method exists now which can treat the total energy and the band structure of these systems simultaneously, a pragmatic approach is chosen. They combine full geometry optimizations (at ab initio level or at semi-empirical self- consistent-field, SCF, level for the large unit cell systems) with subsequent energy band calculations using appropriate non- SCF semi-empirical methods. The energy gaps in these systems are due to the nuclear rearrangements and pertubations caused by chemical substitutions. A broad range of polymers will be studied to find good candidates for very small band gap systems. The Peierls active distortion modes leading to semiconducting gaps in ladder-type polymers have been subject to controversy. Calculations will determine which of these modes leads to the largest energy gain. In the highly doped conducting polymers the location and orientation of dopants will be determined by total energy optimizations. Ab initio calculations will determine the dopant-polymer hybridization and the interchain hopping interaction. The quantitative aspects of bond length equalization upon doping, including the asymetry between donars and acceptors will be determined in conjunction with a new cis-trans isomerization mechanism. The popular qualitative concept of quinoid vs. aromatic forms, which is fundamental in the theory of these polymers, will be put on a quantitative basis through full geometry optimizations. A systematic search for novel groups of compounds with small energy gaps and with two or more energetically close nuclear configurations will be attempted.

拟议的研究是面向问题的：它们的目的是在微观水平上理解，从而获得更多控制的控制因素，这些因子影响了高度掺杂（良好的传导）和原始（半导体）共轭聚合物的结构和电子结构。 它们的低维质会导致非常大的电子 - 普罗替型相互作用和核重排，这是电子 - 普罗顿相互作用和核重排的核心，这是其异常电气和光学特性的核心。 由于现在没有量子机械方法可以同时处理这些系统的总能量和带状结构，因此选择了务实的方法。 他们使用适当的非SCF半经验方法结合了完整的几何优化（从头开始或在半经验的自我一致场，SCF，大型单位细胞系统的水平）和随后的能量频段计算中。 这些系统中的能量差距是由于化学取代引起的核重排和渗透引起的。 将研究广泛的聚合物，以找到非常小的带隙系统的良好候选者。 PEIERL的主动失真模式导致梯形聚合物中的半导体差距已引起争议。 计算将确定哪种模式导致最大的能量增益。 在高度掺杂的导电聚合物中，掺杂剂的位置和方向将由总能量优化确定。 从头算计算将确定掺杂聚合物的杂交和链跳跃相互作用。 掺杂时键均衡的键长均衡的定量方面将与新的顺式传播异构机制结合确定。 在这些聚合物理论中至关重要的奎因类似与芳香族形式的流行定性概念将通过完整的几何优化进行定量基础。 将尝试系统地搜索具有较小能量隙的新型化合物组，并尝试具有两个或多个能量的紧密核构型。