Structure and electronic transport properties of metallic liquids at conditions of planetary cores

行星核心条件下金属液体的结构和电子传输特性

• 批准号: 237280770
• 负责人: Dr. Gerd Steinle-Neumann
• 金额: --
• 依托单位: Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik (BGI)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/237280770?language=en
• 关键词: Structure; electronic; transport; properties; metallic

Electrical conductivity is a key parameter in models of magnetic field generation in planetary interiors through magneto-hydrodynamic convection. Measurements of this key material parameter of liquid metals is not possible to date by experiments at relevant conditions, and dynamo models rely on extrapolations from low pressure/temperature experiments, or more recently on ab-initio calculations combining molecular dynamics and linear response calculations, using the Kubo-Greenwood formulation of transport coefficients. Such calculations have been performed for Fe, Fe-alloys, H, He and H-He mixtures to cover the interior of terrestrial and giant gas planets. These simulations are computationally expensive, and an efficient accurate scheme to determine electrical conductivities is desirable.Here we propose a model that can, at much lower computational costs, provide this information. It is based on Ziman theory of electrical conductivity that uses information on the liquid structure, combined with an internally consistent model of potentials for the electron-electron, electron-atom, and atom-atom interactions. In the proposal we formulate the theory and expand it to multi-component systems. We point out that fitting the liquid structure factor is the critical component in the process, and devise strategies on how this can be done efficiently. Fitting the structure factor in a thermodynamically consistent way and having a transferable electron-atom potential we can then relatively cheaply predict the electrical conductivity for a wide range of conditions. Only limited molecular dynamics simulations to obtain the structure factors are required.In the proposed project we will test and advance this model for liquid aluminum, a free-electron like metal, that we have studied with the Kubo-Greenwood method previously. We will then be able to predict the conductivities of Fe, Fe-light elements and H, He, as well as the H-He system that are relevant to the planetary interiors of terrestrial and giant gas planets, respectively.

电导率是磁流体对流在行星内部产生磁场的模型中的一个关键参数。在相关条件下，通过实验测量液态金属的这一关键材料参数是不可能的，发电机模型依赖于低压/温度实验的外推，或者最近结合分子动力学和线性响应计算的从头计算，使用Kubo-Greenwood输运系数公式。对Fe、Fe合金、H、He和H-He混合物进行了这样的计算，以覆盖类地行星和巨型气体行星的内部。这些模拟在计算上是昂贵的，并且需要一种高效、准确的方案来确定电导率。在这里，我们提出一个模型，该模型可以以更低的计算成本提供这种信息。它基于齐曼的电导率理论，该理论使用关于液体结构的信息，并结合了电子-电子、电子-原子和原子-原子相互作用的内部一致的势模型。在建议中，我们阐述了这一理论，并将其扩展到多组分系统。我们指出，拟合液体结构因子是这一过程中的关键组成部分，并就如何有效地完成这一点制定了策略。以热力学一致的方式拟合结构因子，并具有可转移的电子-原子势，我们就可以相对便宜地预测广泛条件下的电导率。只需要有限的分子动力学模拟来获得结构因子。在拟议的项目中，我们将测试和改进这个模型，用于液态铝，一种类似自由电子的金属，我们以前用Kubo-Greenwood方法研究过。然后，我们将能够预测分别与类地行星和巨型气体行星的行星内部有关的Fe、Fe轻元素和H、He以及H-He系统的电导率。