Nature of the Volume Isotope Effect in Ice
Nature of the Volume Isotope Effect in Ice
复制标题
冰中体积同位素效应的本质
DOI：
10.1103/physrevlett.115.173005
复制
发表时间：
2015
影响因子：
8.6
通讯作者：
and R. M. Wentzcovitch
中科院分区：
文献类型：
--
作者：
K. Umemoto;E. Sugimura;S. de Gironcoli;Y. Nakajima;K. Hirose;Y. Ohishi;and R. M. Wentzcovitch
在冰及其H有序形式的冰中，氢(H)被氢(D)取代，产生体积同位素效应(VIE)的反常形式，即体积膨胀。这与在ICE-VIII及其H无序形式ICE VII中预测的正常VIE(体积收缩)形成对比。在这里，我们用第一性原理准谐计算研究了ICE XI和ICE VIII中的VIE。我们得出的结论是，通过施加压力(从负压开始的冰XI)，然后是第三种类型--具有零点体积收缩的异常VIE，可以在ICE VIII和ICE XI中依次产生正常和异常VIE。后者也应该有助于冰川VIIice X转变中的同位素效应。用X-射线衍射仪在ICE VII中很好地再现了在14.3 GPA和300K时正常VIE和异常VIE之间的预测变化。目前对VIE的讨论是一般性的，结论应该适用于其他固相，可能适用于压力下的液态水，以及其他氢键材料。
The substitution of hydrogen (H) by deuterium (D) in iceand in its H-ordered version, ice XI, produces an anomalous form of volume isotope effect (VIE), i.e., volume expansion. This VIE contrasts with the normal VIE (volume contraction) predicted in ice-VIII and in its H-disordered form, ice VII. Here we investigate the VIE in ice XI and in ice VIII using first principles quasiharmonic calculations. We conclude that normal and anomalous VIEs can be produced in ice VIII and ice XI in sequence by application of pressure (ice XI starting at negative pressures) followed by a third type—anomalous VIE with zero-point volume contraction. The latter should also contribute to the isotope effect in the ice VIIice X transition. The predicted change between normal and anomalous VIE in ice VIII at 14.3 GPa and 300 K is well reproduced experimentally in ice VII using x-ray diffraction measurements. The present discussion of the VIE is general, and conclusions should be applicable to other solid phases of, possibly to liquid water under pressure, and to other H-bonded materials.