Dielectric relaxation spectrum of water studied by the site—site generalized Langevin/modified mode-coupling theory
Dielectric relaxation spectrum of water studied by the site—site generalized Langevin/modified mode-coupling theory
复制标题
位点广义朗之万/修正模式耦合理论研究水的介电弛豫谱
DOI：
10.1080/00268970031000092977
复制
发表时间：
2003
影响因子：
1.7
通讯作者：
F. Hirata
中科院分区：
文献类型：
--
作者：
T. Yamaguchi;S. Chong;F. Hirata
水的介电弛豫谱计算从站点站点广义Langevin/修改模式耦合理论。弛豫的主要部分遵循德拜型函数，并且在高频侧发现与德拜弛豫的小偏差。这种趋势与最近的实验是一致的，虽然绝对弛豫时间不同意与实验值定量。纵向极化函数的时间发展类似于记忆函数的介电部分，我们认为这是因为介电摩擦主导了水的偶极矩的集体重定向。我们进行了计算与不同的介电常数使用参考相互作用网站模型积分方程，并发现之间的介电弛豫和纵向极化弛豫的时间尺度的大差距，导致德拜型介电弛豫在我们的理论时，介质摩擦是占主导地位的摩擦上的集体重定向的偶极矩。也就是说，纵向极化弛豫足够快以被认为是介电弛豫过程的白色噪声，使得弛豫变成马尔可夫过程。两个弛豫时间之间的大差距源于由于水的大介电常数而引起的大的局部场校正。我们还认为，在高频侧偏离德拜弛豫是低波数区纵向极化弛豫的长时间部分引起的慢记忆的表现。
The dielectric relaxation spectrum of water is calculated from the site-site generalized Langevin/modified mode-coupling theory. The main part of the relaxation follows the Debye-type function, and a small deviation from the Debye relaxation is found on the high-frequency side. This tendency is consistent with recent experiments, although the absolute relaxation time does not agree with the experimental value quantitatively. The time development of the longitudinal polarization function resembles the dielectric part of the memory function, and we consider that this is because the dielectric friction dominates the collective reorientation of the dipole moment of water. We performed calculations with different dielectric constants using the reference interaction-site model integral equation, and found that the large gap between the time scales of the dielectric relaxation and the longitudinal polarization relaxation causes the Debye-type dielectric relaxation in our theory when the dielectric friction is dominant in the friction on the collective reorientation of the dipole moment. Namely, the longitudinal polarization relaxation is fast enough to be considered as a white noise to the dielectric relaxation process, so that the relaxation becomes a Markov process. The large gap between the two relaxation times originates from a large local field correction owing to the large dielectric constant of water. It is also suggested that the deviation from the Debye relaxation at the high-frequency side is the manifestation of the slow memory caused by the long-time part of the longitudinal polarization relaxation in the low-wavenumber region.
影响因子：
--
作者：
BERENDSEN, HJC;GRIGERA, JR;STRAATSMA, TP
通讯作者：
STRAATSMA, TP