Institute for Theoretical Physics, University of Tübingen, 72076 Tübingen, Germany.
Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
J Chem Phys. 2018 Mar 14;148(10):104501. doi: 10.1063/1.5019447.
Using dynamical density functional theory (DDFT), we theoretically study Brownian self-diffusion and structural relaxation of hard disks and compare to experimental results on quasi two-dimensional colloidal hard spheres. To this end, we calculate the self-van Hove correlation function and distinct van Hove correlation function by extending a recently proposed DDFT-approach for three-dimensional systems to two dimensions. We find that the theoretical results for both self-part and distinct part of the van Hove function are in very good quantitative agreement with the experiments up to relatively high fluid packing fractions of roughly 0.60. However, at even higher densities, deviations between the experiment and the theoretical approach become clearly visible. Upon increasing packing fraction, in experiments, the short-time self-diffusive behavior is strongly affected by hydrodynamic effects and leads to a significant decrease in the respective mean-squared displacement. By contrast, and in accordance with previous simulation studies, the present DDFT, which neglects hydrodynamic effects, shows no dependence on the particle density for this quantity.
利用动力密度泛函理论（DDFT），我们从理论上研究了硬磁盘的布朗自扩散和结构弛豫，并将其与准二维胶体硬球的实验结果进行了比较。为此，我们通过将最近提出的用于三维系统的 DDFT 方法扩展到二维，计算了自配分函数和独特配分函数的自和夫函数。我们发现，直到相对较高的流体填充分数（约 0.60），理论结果在自部分和独特部分的夫函数方面与实验结果非常吻合。然而，在更高的密度下，实验和理论方法之间的偏差变得非常明显。随着填充分数的增加，在实验中，短时间自扩散行为受到流体动力学效应的强烈影响，导致相应的均方位移显著减小。相比之下，根据之前的模拟研究，本研究中忽略流体动力学效应的 DDFT 对于该量没有显示出对粒子密度的依赖性。
