Car-Parrinello Molecular Dynamics Study for the Isotope Effect on OH Vibration in Ice Ih
作者:Yeohoon Yoon
DOI:10.5012/bkcs.2013.34.2.553
日期:2013.2.20
The stretching vibration of OH of ice Ih is studied by Car-Parrinello molecular dynamics in regarding the effect of mixed H/D contamination while the vibrational spectrum is considered by velocity-velocity autocorrelations of the sampled ensemble. When hydrogen atoms are immersed randomly into the deuterated ice, a typical vibrational frequency of OH stretching mode is observed to be similar to that from the pure $H_2O$ ice. When focusing on the correlation of isolated neighboring OH stretching, a narrower and blue shifted peak is observed at the high frequency range as a result of the screening from the complex many body correlations by $D_2O$ environment. It is also specifically related to the symmetric intermolecular correlations between neighboring OH stretching modes. More enhanced high frequency range can be explained by the expansion of such two body correlations to collective many body correlations among all possible OH stretching modes. This contribution becomes important when it involves in chemical interactions via excitation of such vibrational states.
利用 Car-Parrinello 分子动力学研究了 Ih 冰的 OH 拉伸振动,其中考虑到了 H/D 混合污染的影响,同时通过采样集合的速度-速度自相关性考虑了振动谱。当氢原子随机浸入氚化冰时,观察到 OH 拉伸模式的典型振动频率与纯 $H_2O$ 冰的振动频率相似。当关注孤立邻域 OH 拉伸的相关性时,由于 $D_2O$ 环境屏蔽了复杂的多体相关性,在高频范围观察到一个较窄的蓝移峰值。这也与相邻 OH 拉伸模式之间的对称分子间相关性密切相关。这种两体相关性扩展到所有可能的 OH 拉伸模式之间的集体多体相关性,可以解释更多增强的高频范围。当涉及到通过激发这些振动状态而产生的化学相互作用时,这种贡献就变得非常重要。