Skarmoutsos Ioannis, Samios Jannis
Department of Chemistry, Laboratory of Physical Chemistry, University of Athens, Panepistimiopolis 157-71, Athens, Greece.
J Phys Chem B. 2006 Nov 2;110(43):21931-7. doi: 10.1021/jp060955p.
Molecular dynamics atomistic simulations in the canonical ensemble (NVT-MD) have been used to investigate the "Local Density Inhomogeneities and their Dynamics" in pure supercritical water. The simulations were carried out along a near-critical isotherm (Tr = T/Tc = 1.03) and for a wide range of densities below and above the critical one (0.2 rho(c) - 2.0 rho(c)). The results obtained reveal the existence of significant local density augmentation effects, which are found to be sufficiently larger in comparison to those reported for nonassociated fluids. The time evolution of the local density distribution around each molecule was studied in terms of the appropriate time correlation functions C(Delta)rhol(t). It is found that the shape of these functions changes significantly by increasing the density of the fluid. Finally, the local density reorganization times for the first and second coordination shell derived from these correlations exhibit a decreasing behavior by increasing the density of the system, signifying the density effect upon the dynamics of the local environment around each molecule.
在正则系综（NVT - MD）中进行的分子动力学原子模拟已被用于研究纯超临界水中的“局部密度不均匀性及其动力学”。模拟是沿着一条近临界等温线（Tr = T/Tc = 1.03）进行的，且涵盖了临界密度上下很宽范围的密度（0.2ρ(c) - 2.0ρ(c)）。所获得的结果揭示了显著的局部密度增强效应的存在，发现这些效应与报道的非缔合流体相比要大得多。根据适当的时间关联函数C(Δ)rhol(t)研究了每个分子周围局部密度分布的时间演化。发现通过增加流体密度，这些函数的形状会发生显著变化。最后，从这些关联推导得出的第一和第二配位层的局部密度重组时间随着系统密度的增加呈现出下降趋势，这表明密度对每个分子周围局部环境动力学的影响。
