Appraisal of the realistic accuracy of molecular dynamics of high-pressure hydrogen
Appraisal of the realistic accuracy of molecular dynamics of high-pressure hydrogen
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DOI：
10.1080/23311940.2015.1049477
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发表时间：
2015-01-01
期刊：
影响因子：
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通讯作者：
Magdau, Ioan B.
中科院分区：
文献类型：
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作者：
Ackland, Graeme J.;Magdau, Ioan B.
分子动力学（MD）是研究材料高温行为的有力手段.然而，在实践中，它的有效性表示真实的系统是有限的力的精度，有限尺寸效应，量化和平衡方法。在本文中，我们报告和讨论了一些计算进行了MD上的高压氢，审查了一些来源的错误，其中忽略零点振动是最大的定量。我们表明，模拟使用从头算MD与PBE功能预测一个大的稳定领域的分子Cmca4结构的压力刚刚高于目前的实验中所取得的稳定范围以上的混合分子分层相IV。然而，模拟中的各种错误都指向一个小得多的稳定范围，以及基于低配位网络或原子链的非分子相的可能性。
Molecular dynamics (MD) is a powerful method for studying the behaviour of materials at high temperature. In practice, however, its effectiveness in representing real systems is limited by the accuracy of the forces, finite size effects, quantization and equilibration methods. In this paper, we report and discuss some calculations carried out using MD on high-pressure hydrogen, reviewing a number of sources of error, of which the neglect of zero-point vibrations is quantitatively the largest. We show that simulations using ab initio MD with the PBE functional predict a large stability field for the molecular Cmca4 structure at pressures just above those achieved in current experiments above the stability range of the mixed molecular layered Phase IV. However, the various errors in the simulation all point towards a much smaller stability range, and the likelihood of a non-molecular phase based on low-coordination networks or chains of atoms.