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arXiv 1012.1612cond-mat.soft
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关于流体动力学的密度标度

On the density scaling of liquid dynamics

Daniel Fragiadakis, C. Michael Roland

摘要:

弛豫数据作为乘积变量TV^γ的函数的叠加,其中T是温度,V是比容,γ是材料常数,这是对大约100种液体和聚合物证明的实验事实。这样的标度行为将导致从具有逆幂律(IPL)的形式的分子间的潜力,这表明IPL是一个很好的近似在相关范围内的分子间距离的某些弛豫性质。然而,强脉冲光液体的缩放特性的推导是基于减少的量,例如,减少的弛豫时间等于T^1/2 V ^-1/3乘以实际弛豫时间。在过冷区,使用约化单位与未约化单位的标度之间的差异可以忽略不计;然而,在较高温度下,差异可能很大,这是标度崩溃的原因,并导致标度指数的不同值。只有用约化量得到的γ才能与分子间势有明显的关系。

英文摘要:

Superpositioning of relaxation data as a function of the product variable TV^γ, where T is temperature, V the specific volume, and γ a material constant, is an experimental fact demonstrated for approximately 100 liquids and polymers. Such scaling behavior would result from the intermolecular potential having the form of an inverse power law (IPL), suggesting that an IPL is a good approximation for certain relaxation properties over the relevant range of intermolecular distances. However, the derivation of the scaling property of an IPL liquid is based on reduced quantities, for example, the reduced relaxation time equal to T^1/2V^-1/3 times the actual relaxation time. The difference between scaling using reduced rather than unreduced units is negligible in the supercooled regime; however, at higher temperature the difference can be substantial, accounting for the purported breakdown of the scaling and giving rise to different values of the scaling exponent. Only the γ obtained using reduced quantities can be sensibly related to the intermolecular potential.

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