Quantum dynamics at the nanoscale

纳米尺度的量子动力学

• 批准号: 0927345
• 负责人: Kalman Varga
• 金额: $ 27万
• 依托单位: Vanderbilt University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927345&HistoricalAwards=false
• 关键词: Quantum; dynamics; nanoscale

Quantum dynamics plays an extraordinarily important role at the nanoscale level. Dynamics is an unavoidable ingredient at the nanoscale, whether the movement is electronic, ionic, or a near-equilibrium fluctuation. Dynamical processes occur when one wishes to control the nanoscale, e.g., to avoid local failures of gate dielectrics, to manipulate structures by electronic excitation, or to use the spin degrees of freedom in quantum information processing. To describe and understand any process at the nanoscale level the essential complement to equilibrium structural information is dynamics. The ultimate timescale for atomic rearrangements in chemical and material systems is known to be that of a single vibrational period (~100 fs). Many important phenomena have their origins in processes that occur on this timescale. To get an insight of the dynamics at the nanoscale one needs a well-developed general method for the atomic-level structural description of short-lived transient states. The object of this proposal is to study electron dynamics at the nanoscale using a time-dependent first-principles framework by coupling the Schrodinger and the Maxwell equations. This proposal addresses the theoretical and quantum simulation challenges of nanoscale dynamics. The research will focus on simulating nonlinear dynamics in nanoscale systems, such as response to femtosecond laser pulses, dynamics of Fermi degenerate electron beams, and laser excitation of coherent acoustic phonon modes. The theoretical description and computational simulation of these systems is challenging because for proper description of electron dynamics one should use time-dependent quantum mechanical approach with time-varying electromagnetic fields. In certain cases, the quantum nuclear dynamics also plays important role and one has to go beyond the Born-Oppenheimer approach. The goal of this proposal is to provide a rigorous atomistic quantum mechanical framework to simulate the time-dependent processes at the nanoscale.

量子动力学在纳米尺度上发挥着极其重要的作用。无论运动是电子的、离子的还是接近平衡的波动，动力学都是纳米尺度上不可避免的因素。当人们希望控制纳米尺度时，例如避免栅极电介质的局部故障、通过电子激发操纵结构或在量子信息处理中使用自旋自由度，就会发生动态过程。为了描述和理解纳米级的任何过程，平衡结构信息的必要补充是动力学。已知化学和材料系统中原子重排的最终时间尺度是单个振动周期（~100 fs）。 许多重要现象都起源于这个时间尺度上发生的过程。为了深入了解纳米尺度的动力学，我们需要一种成熟的通用方法来描述短暂瞬态的原子级结构。该提案的目的是通过耦合薛定谔方程和麦克斯韦方程，使用依赖时间的第一原理框架来研究纳米尺度的电子动力学。该提案解决了纳米级动力学的理论和量子模拟挑战。该研究将侧重于模拟纳米级系统中的非线性动力学，例如对飞秒激光脉冲的响应、费米简并电子束的动力学以及相干声声子模式的激光激发。这些系统的理论描述和计算模拟具有挑战性，因为为了正确描述电子动力学，应该使用具有时变电磁场的时间相关量子力学方法。在某些情况下，量子核动力学也发挥着重要作用，人们必须超越玻恩-奥本海默方法。该提案的目标是提供严格的原子量子力学框架来模拟纳米尺度的时间相关过程。