Diffusion and electrical conductivity in water at ultrahigh pressures
Diffusion and electrical conductivity in water at ultrahigh pressures
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DOI：
10.1103/physrevb.82.174108
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发表时间：
2010-11-10
影响因子：
3.7
通讯作者：
Redmer, Ronald
中科院分区：
文献类型：
--
作者：
French, Martin;Mattsson, Thomas R.;Redmer, Ronald
我们计算的电导率的水的压力高达80毫巴和温度高达130 000 K的相关行星物理学通过使用从头算分子动力学模拟。电子系统内的密度泛函理论和电子电导率的Kubo-Greenwood公式的评价得到。离子电导率通过扩散系数确定。我们的计算再现了误差条内的大部分可用的实验电导率数据，而Mitchell和Nellis测量的电导率平台无法再现。在高密度的压力诱导的非金属到金属的过渡预测内的超离子相。此外，我们研究了交换和相关性对电子电导率的影响，更详细地应用标准的广义梯度近似和混合功能，以及包括屏蔽Fock交换。后一种处理产生更大的带隙，因此更可靠的电导率，特别是在非金属-金属过渡区。这些结果是相关的输入未来的内部和发电机模型的巨大，富含水的行星。
We calculate the electrical conductivity of water for ultrahigh pressures up to 80 Mbar and temperatures up to 130 000 K as relevant for planetary physics by using ab initio molecular-dynamics simulations. The electron system is treated within density-functional theory and the electronic conductivity is obtained from an evaluation of the Kubo-Greenwood formula. The ionic conductivity is determined via diffusion coefficients. Our calculations reproduce most of the available experimental conductivity data within the error bars while the conductivity plateau measured by Mitchell and Nellis cannot be reproduced. At high densities a pressure-induced nonmetal-to-metal transition is predicted within the superionic phase. Furthermore, we study the influence of exchange and correlations on the electronic conductivity in more detail by applying a standard generalized gradient approximation and a hybrid functional as well that includes screened Fock exchange. The latter treatment yields a larger band gap and thus more reliable electrical conductivities, especially in the region of the nonmetal-to-metal transition. These results are relevant as input for future interior and dynamo models of giant, water-rich planets.