On the origin of the redshift of the OH stretch in Ice Ih: evidence from the momentum distribution of the protons and the infrared spectral density
On the origin of the redshift of the OH stretch in Ice Ih: evidence from the momentum distribution of the protons and the infrared spectral density
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DOI：
10.1039/b605410b
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发表时间：
2006-01-01
影响因子：
3.3
通讯作者：
Dosch, H.
中科院分区：
文献类型：
--
作者：
Burnham, C. J.;Reiter, G. F.;Dosch, H.
最近对水和冰中动量分布的测量表明，质子在冰中的势比在水或自由单体中的势要软得多。这与在振动光谱中观察到的大红移大致一致。我们发现，现有的水模型不能重现动量分布，它把分子内势看作是通过氢键保持不变的。此外，即使他们可以实质上解释红移，他们也不能解释从单体到冰河的红外光谱中观察到的强度的大幅增加。我们表明，键偶极导数项的包含对于解释红外光谱中观察到的强度是必不可少的。虽然这一项是质子有效势软化的部分原因，但我们表明，要与观察到的动量分布最好地符合，需要进一步软化分子内势的谐和分量。介绍了一种用路径积分计算动量分布的简正波分子动力学算法。
Recent measurements of the momentum distribution in water and ice have shown that the proton is in a considerably softer potential in ice Ih than in water or the free monomer. This is broadly consistent with the large red shift observed in the vibrational spectrum. We show that existing water models, which treat the intramolecular potential as unchanged by the hydrogen bonding are unable to reproduce the momentum distribution. In addition, even if they can substantially explain the red shift they are unable to explain the large increase in intensity observed in the infrared spectrum in going from the monomer to ice Ih. We show that the inclusion of a bond dipole derivative term is essential to explain the observed intensities in the infrared spectrum. Though this term is partially responsible for the softening of the effective potential of the proton we show that best agreement with the observed momentum distribution requires a further softening of the harmonic component of the intramolecular potential. We introduce an efficient normal-mode molecular dynamics algorithm for calculating the momentum distribution with path-integrals.