QMHP: Nonequilibrium Green function modeling of coupled electron and phonon transport in nanoscale thermoelectric devices

该项目将帮助我们了解芯片作为能源使用的更高效率的根本障碍，希望我们能够通过利用这种理解来实现未来的能源突破。更具体地说，该项目将开发一个量子传输框架，通过大规模并行计算实现，以研究耦合电子和声子（即，原子的振动）在真实的纳米结构中传播。最近的实验和纳米纤维的进展点燃了探索的热流和热电纳米线和分子结。然而，这种系统的理论和计算研究是落后的，考虑电子和声子电流独立。该方法是非平衡绿色函数形式主义结合第一原理方法的情况下，分子结或与sermi经验模型的nanows.Intellectual优点：非平衡量子多体问题所造成的电子和声子之间的非弹性耦合有巨大的计算复杂性，这已经阻止了微观一致的治疗电荷传输和能量传输的平等地位。提出的新算法开发来解决这个具有挑战性的问题有可能成为同类中的第一个。更广泛的影响：热电转换温度梯度成电压，反之亦然。所提出的将石墨烯纳米带或硅纳米线与小分子或纳米孔组合的装置的热电优值的优化可以导致用于从废热或用于电子电路的固态冷却器发电的商业上可行的技术。拟议的研究将为研究生提供非平衡量子统计力学，纳米器件工程和高性能计算先进技术的优秀培训。外联活动将包括举办“面向高中教师和学生的纳米科学和纳米技术”讲习班，在暑期学校讲课，以及举办计算电子学国际讲习班。

This project will help us understand the fundamental barriers to higher efficiency in chips used as energy sources, in hopes that we can achieve future breakthroughs in energy by harnessing that understanding.More specifically, the project will develop a quantum transport framework, implemented via massively parallel computation, to study coupled electron and phonon (i.e., vibrations of atoms) propagation in realistic nanostructures. The recent experimental and nanofabrication advances have ignited the exploration of heat flow and thermoelectricity in nanowires and molecular junctions. However, the theoretical and computational studies of such systems are lagging behind by considering electron and phonon currents independently. The approach is nonequilibrium Green function formalism combined with either first-principles methodology in the case of molecular junctions or with sermi-empirical models in the case of nanowires.Intellectual Merit:The nonequilibrium quantum many-body problem posed by the inelastic coupling between electrons and phonons has enormous computational complexity which has prevented microscopic consistent treatment of both charge transport and energy transport on an equal footing. The proposed novel algorithm development to tackle this challenging problem has a potential to be the first of its kind.Broader Impact:Thermoelectrics transform temperature gradients into electric voltage and vice versa. The optimization of the thermoelectric figure of merit for the proposed devices combining graphene nanoribbons or silicon nanowires with small molecules or nanopores could lead to commercially viable technologies for generation of electricity from waste heat or solid-state coolers for electronic circuits. The proposed research will offer excellent training for graduate students in advanced techniques of nonequilibrium quantum statistical mechanics, nanoscale device engineering, and high-performance computing. The outreach activities will include organization of workshops on "Nanoscience and nanotechnology for high school teachers and students," lecturing at summer schools, and organization of international workshops on computational electronics.