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

这个项目将帮助我们了解芯片用作能源的更高效率的根本障碍，希望我们可以通过利用这种理解来实现未来在能源方面的突破。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来实现，以研究电子和声子在现实纳米结构中的耦合传播。最近的实验和纳米制造的进展点燃了对纳米线和分子结中热流和热电的探索。然而，对这类系统的理论和计算研究相对滞后，单独考虑电子和声子流。这种方法是非平衡格林函数形式主义，在分子结的情况下结合第一原理方法，在纳米线的情况下结合系列经验模型。智力上的优点：由电子和声子之间的非弹性耦合引起的非平衡量子多体问题具有巨大的计算复杂性，这阻碍了对电荷输运和能量输运的微观一致处理。为解决这一具有挑战性的问题而提出的新算法开发有可能是此类问题中的第一个。广泛的影响：热电技术将温度梯度转换为电压，反之亦然。将石墨烯纳米带或硅纳米线与小分子或纳米孔结合在一起的拟议设备的热电优值系数的优化，可能会导致商业上可行的技术，利用废热发电或电子电路的固态冷却器。拟议的研究将在非平衡量子统计力学、纳米设备工程和高性能计算的高级技术方面为研究生提供出色的培训。外展活动将包括为高中教师和学生组织关于“纳米科学和纳米技术”的讲习班，在暑期学校讲课，以及组织关于计算电子的国际讲习班。

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.