Efficacious calculation of Raman spectra in high pressure hydrogen
Efficacious calculation of Raman spectra in high pressure hydrogen
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DOI：
10.1080/08957959.2013.856897
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发表时间：
2014-06-01
影响因子：
2
通讯作者：
Magdau, I. B.
中科院分区：
文献类型：
--
作者：
Ackland, G. J.;Magdau, I. B.
我们提出并评估了一种从分子动力学计算中模拟拉曼光谱的有效方法，而无需定义简正模。我们将该方法应用于高温相IV中的高压氢：一种塑料晶体，其中固定声子本征模的传统图像被打破。将轨迹投影到同相分子伸展上的速度比极化率计算快了许多个数量级，从而允许在高温下进行统计平均。将模拟扩展到亚稳态区域，并在不同的时间尺度上确定了与对称破缺相关的几个区域，这些区域在当前实验的可分辨极限下显示了拉曼光谱的特征。在这篇文章中，我们集中在方法学上，前一篇论文[Magdau IB，Ackland GJ.]对第四相氢的结构给出了更全面的描述。氢气中高压相III和IV的识别：用分子动力学模拟拉曼光谱。PHYS Rev B.2013；87：174110]。
We present and evaluate an efficient method for simulating Raman spectra from molecular dynamics calculations without defining normal modes. We apply the method to high pressure hydrogen in the high-temperature Phase IV: a plastic crystal in which the conventional picture of fixed phonon eigenmodes breaks down. Projecting trajectories onto in-phase molecular stretches is shown to be many orders of magnitude faster than polarisability calculations, allowing statistical averaging at high-temperature. The simulations are extended into metastable regimes and identify several regimes associated with symmetry-breaking on different timescales, which are shown to exhibit features in the Raman spectra at the current experimental limit of resolvability. In this paper we have concentrated on the methodology, a fuller description of the structure of Phase IV hydrogen is given in a previous paper [Magdau IB, Ackland GJ. Identification of high-pressure phases III and IV in hydrogen: simulating Raman spectra using molecular dynamics. Phys Rev B. 2013;87:174110].