Effect of Electric Field Orientation on the Mechanical and Electrical Properties of Water Ices: An Ab-initio Study
Effect of Electric Field Orientation on the Mechanical and Electrical Properties of Water Ices: An Ab-initio Study
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DOI：
10.1021/jp507376v
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发表时间：
2014-11-06
影响因子：
3.3
通讯作者：
Saitta, A. Marco
中科院分区：
文献类型：
--
作者：
Cassone, Giuseppe;Giaquinta, Paolo V.;Saitta, A. Marco
我们提出了一个第一性原理研究的性质，普通的六角形冰（相Ih）和它的质子有序的版本（相XI）的作用下的静电场。除了离子电流-电压图之外，我们还计算了对场的机械响应;我们还分析了质子转移机制的其他几个微观方面，特别强调了氧亚晶格在驱动分子解离中所起的作用。我们进一步研究的拓扑方面的机械和电气响应的取向外磁场沿着两个不同的结晶方向在两个冰样品。与冰Ih不同，冰XI在探测的场强范围内显示出各向异性行为。事实上，当场的方向与铁电轴重合时，在给定的场强之外观察到持续的分子解离和质子转移事件;相反，当场沿沿着另一对称轴取向时，这两个过程表现出不同的激活阈值。分子离解的基本机制在固态和液态水中似乎是相同的，与电场的方向无关。
We present a first-principles study of the properties of ordinary hexagonal ice (phase Ih) and of its proton-ordered version (phase XI) under the action of static electric fields. We compute the mechanical response to the field in addition to the ionic current-voltage diagrams; we also analyze several other microscopic aspects of the proton transfer mechanism, with particular emphasis on the role played by the oxygen sublattice in driving molecular dissociation. We further study the topological aspects of the mechanical and electrical responses by orienting the external field along two different crystalline directions in both ice samples. At variance with ice Ih, ice XI displays an anisotropic behavior in the range of explored field intensities. In fact, when the direction of the field coincides with the ferroelectric axis, sustained molecular dissociation and proton transfer events are both observed just beyond a given field intensity; instead, the two processes exhibit different activation thresholds when the field is oriented along another symmetry axis. The underlying mechanism of molecular dissociation appears to be the same in solid and liquid water independently of the direction of the field.