Multiscale modeling and simulation of molecular devices and systems

微电子集成电路可能是有史以来最复杂的人工系统。他们的“成功故事”基于两个事实：一个是技术，另一个是设计。技术基础是普遍的：由于电子元件和它们的相互连接被缩小到几乎原子的尺寸，并且有可能在一个晶圆上挤压数十亿个设备，人们可以以合理的价格生产一个非常大（和复杂）的系统。与设计相关的基础同样重要，但经常被忽视：这是分层的、模块化的工程方法。电子设备的电路模型是建立在物理模型的基础上的，电路模型是建筑概念的基础。这种描述层次的清晰分离有助于复杂系统的设计。现在已经证实，单分子器件显示出可以使它们成为有用的电子元件的电学特性，并且大量的研究致力于将分子组装和集成成类似电路的排列。另一方面，到目前为止，分子电路还没有可行的设计方法。我们提出的研究目标是开发一种多尺度建模方法来描述分子系统，并立即将其应用于新颖的、有前途的计算架构的模拟。利用分子系统的密度泛函方法（纳米级）和整个器件的漂移扩散和蒙特卡罗工具（微尺度级），我们将研究单分子器件在其环境中的行为，从而包括接触的影响，分子器件之间的电磁相互作用，散热，波动。由此，我们将从体系结构的角度（宏观层面）提取所需的参数来描述系统。在架构设计中，我们将集中于两种有前途的分子尺度架构：横杆型电路和场耦合架构。一个很大的重点将放在分子和输入/输出电路的接口。分子电子学的关键问题是分子实体是否可以像电子实体一样集成在复杂的电路中，如果答案是肯定的，那么什么是最适合这样做的架构概念。我们的研究将使我们更接近这个问题的答案。

Microelectronic integrated circuits are probably the most complex artificial systems ever created. Their `success story¿ is based on two facts: one is technological and the other one is designrelated. The technological base is commonplace: since electronic components and their interconnections are scaled down to almost atomic dimensions and it is possible to squeeze billions of devices on a single wafer, one can produce a very large (and complex) system for a reasonable price. The design- related base is equally important but often overlooked: this is the hierarchical, modular engineering approach. Circuit models of electronic devices are based on physical models, and circuit models are the foundations of architectural concepts. This clear separation of the levels of description facilitates the design of complex systems.It is now confirmed that single-molecule devices show electrical characteristics that could make them useful electronic components and a large amount of research is dedicated to the assembly and integration of molecules into circuit-like arrangements. On the other hand, no viable design methodology emerged so far for molecular circuits.The goal of our proposed research is to develop a multiscale modelling approach to the description of molecular systems and immediately apply it to the simulation of novel, promising computing architectures.Using Density Functional approaches for the molecular system (nanoscale level) and drift-diffusion and Monte Carlo tools for the whole devices (microscale level) we will investigate the behaviour of single-molecule devices in their environment, thus including the effect of contacts, electromagnetic interaction among molecular devices, thermal dissipation, fluctuations. From this, we will extract the required parameters to describe the system for an architectural point of view (macroscale level). In the architecture design we will concentrate on two promising molecular-scale architectures: crossbar-type circuits and field-coupled architectures. A large emphasis will be put on the interface of the molecules and the input / output circuitry. The key questions of molecular electronics whether molecular entities can be integrated in complex circuitry, like their electronic counterparts, and if the answer is yes, what are the most suitable architecture concepts for doing this. Our research should bring us closer to the answer of this problem.