Meyer Edmund R, Ticknor Christopher, Bethkenhagen Mandy, Hamel Sebastien, Redmer Ronald, Kress Joel D, Collins Lee A
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Institut für Physik, Universität Rostock, D-18501 Rostock, Germany.
J Chem Phys. 2015 Oct 28;143(16):164513. doi: 10.1063/1.4934626.
We have performed finite-temperature density functional theory molecular dynamics simulations on dense methane, ammonia, and water mixtures (CH4:NH3:H2O) for various compositions and temperatures (2000 K ≤ T ≤ 10,000 K) that span a set of possible conditions in the interiors of ice-giant exoplanets. The equation-of-state, pair distribution functions, and bond autocorrelation functions (BACF) were used to probe the structure and dynamics of these complex fluids. In particular, an improvement to the choice of the cutoff in the BACF was developed that allowed analysis refinements for density and temperature effects. We note the relative changes in the nature of these systems engendered by variations in the concentration ratios. A basic tenet emerges from all these comparisons that varying the relative amounts of the three heavy components (C,N,O) can effect considerable changes in the nature of the fluid and may in turn have ramifications for the structure and composition of various planetary layers.
我们对稠密的甲烷、氨和水混合物（CH4:NH3:H2O）进行了有限温度密度泛函理论分子动力学模拟，研究了多种成分和温度（2000 K ≤ T ≤ 10,000 K），这些条件涵盖了冰巨星系外行星内部的一系列可能情况。状态方程、对分布函数和键自相关函数（BACF）被用于探究这些复杂流体的结构和动力学。特别是，对BACF中截止值的选择进行了改进，从而能够对密度和温度效应进行更精细的分析。我们注意到浓度比变化所导致的这些系统性质的相对变化。所有这些比较都得出一个基本观点，即改变三种重元素（C、N、O）的相对含量会对流体性质产生相当大的影响，进而可能对不同行星层的结构和组成产生影响。
