INSTANTANEOUS NORMAL-MODE ANALYSIS OF LIQUID WATER
INSTANTANEOUS NORMAL-MODE ANALYSIS OF LIQUID WATER
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DOI：
10.1063/1.467027
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发表时间：
1994-05-01
影响因子：
4.4
通讯作者：
STRATT, RM
中科院分区：
文献类型：
--
作者：
CHO, M;FLEMING, GR;STRATT, RM
我们提出了一种基于计算机模拟的一组液体构型的室温下液态水的瞬时正态分析，并将结果与类似的固有结构计算进行了比较。通过从特征向量中计算适当的投影，首先获得了对每个瞬时正态模态的单独的平移和旋转贡献。然后借助逆参与比（大致是每个模态所涉及的自由度数的倒数）来量化不同模态的局部化程度。瞬时正态模态也包含了一个隐含的图像，即当一个人在液体的高维构型空间中从一个点移动到另一个点时，潜在表面的地形是如何变化的。为了帮助我们理解这种地形，我们使用瞬时正态模式来计算预测的高度和最近的极值电位的位置。最终的结果是，至少在液态水中，低频模式似乎反映了最大规模的结构转变。这种转变的详细动力学可能超出了瞬时正态模态的形式，但我们确实发现，短时动态量，如角速度自相关函数，被瞬时模态描述得非常好。
We present an instantaneous-normal-mode analysis of liquid water at room temperature based on a computer simulated set of liquid configurations and we compare the results to analogous inherent-structure calculations. The separate translational and rotational contributions to each instantaneous normal mode are first obtained by computing the appropriate projectors from the eigenvectors. The extent of localization of the different kinds of modes is then quantified with the aid of the inverse participation ratio-roughly the reciprocal of the number of degrees of freedom involved in each mode. The instantaneous normal modes also carry along with them an implicit picture of how the topography of the potential surface changes as one moves from point to point in the very-high dimensional configuration space of a liquid. To help us understand this topography, we use the instantaneous normal modes to compute the predicted heights and locations of the nearest extrema of the potential. The net result is that in liquid water, at least, it is the low frequency modes that seem to reflect the largest-scale structural transitions. The detailed dynamics of such transitions are probably outside of the instantaneous-normal-mode formalism, but we do find that short-time dynamical quantities, such as the angular velocity autocorrelation functions, are described extraordinarily well by the instantaneous modes.