Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland.
J Phys Condens Matter. 2010 Nov 10;22(44):445403. doi: 10.1088/0953-8984/22/44/445403. Epub 2010 Oct 22.
The structure, lattice dynamics and mechanical properties of magnesium hydroxide have been investigated by static density functional theory calculations as well as ab initio molecular dynamics. The hypothesis of a superstructure existing in the lattice formed by the hydrogen atoms has been tested. The elastic constants of the material have been calculated with a static deformations approach and are in fair agreement with the experimental data. The hydrogen subsystem structure exhibits signs of disordered behaviour while maintaining correlations between the angular positions of neighbouring atoms. We establish that the essential angular correlations between hydrogen positions are maintained to a temperature of at least 150 K and that they are well described by a physically motivated probabilistic model. The rotational degree of freedom appears to be decoupled from the lattice directions above 30 K.
采用静态密度泛函理论计算和从头算分子动力学研究了氢氧化镁的结构、晶格动力学和力学性能。检验了在由氢原子形成的晶格中存在超结构的假设。采用静态变形方法计算了材料的弹性常数，与实验数据吻合良好。氢子系统结构表现出无序行为的迹象，同时保持了相邻原子角位置之间的相关性。我们确定，在至少 150 K 的温度下，氢位置之间的基本角相关性得以维持，并且可以通过物理上合理的概率模型很好地描述它们。在 30 K 以上，旋转自由度似乎与晶格方向解耦。
