论文标题
实验确认液态振动密度的通用定律
Experimental Confirmation of the Universal Law for the Vibrational Density of States of Liquids
论文作者
论文摘要
描述液体状态振动声子密度（VDOS）的分析模型长期以来难以捉摸，这主要是由于很难处理低能区域中占主导地位的虚构模式，如瞬时正常模式（INM）方法所述。然而，Zaccone和Baggioli最近开发了一种基于阻尼Langevin液体动力学的模型。该模型被认为是液态振动密度的通用定律。对于固体，液体的通用定律与Debye定律G（ω）〜Ω2不同，在低能区域中揭示了线性关系G（ω）〜Ω。通用法律已通过计算机模拟VDOS成功验证了Lennard-Jones液体的VDO。我们通过通过非弹性中子散射在包括水，液体金属和聚合物液体在内的真实液体系统上测量的实验VDOS进一步确认了这一通用定律。我们已经应用了此模型，并为每种液体的短时动力学提取了有效的松弛率。该模型已在特定热量的鉴定中得到了进一步评估。结果已与现有的实验数据以及不同方法获得的值进行了比较。
An analytical model describing the vibrational phonon density of states (VDOS) of liquids has long been elusive, mainly due to the difficulty in dealing with the imaginary modes dominant in the low-energy region, as described by the instantaneous normal mode (INM) approach. Nevertheless, Zaccone and Baggioli have recently developed such a model based on overdamped Langevin liquid dynamics. The model was proposed to be the universal law for the vibrational density of states of liquids. Distinct from the Debye law, g(ω) ~ ω2, for solids, the universal law for liquids reveals a linear relationship, g(ω) ~ ω, in the low-energy region. The universal law has been successfully verified with computer simulated VDOS for Lennard-Jones liquids. We further confirm this universal law with experimental VDOS measured by inelastic neutron scattering on real liquid systems including water, liquid metal, and polymer liquids. We have applied this model and extracted the effective relaxation rate for the short time dynamics for each liquid. The model has been further evaluated in the predication of the specific heat. The results have been compared with the existing experimental data as well as with values obtained by different approaches.
