Cromie S R T, Ballone P
Atomistic Simulation Centre, Queen's University Belfast, Belfast BT7 1NN, United Kingdom.
J Chem Phys. 2009 Jul 21;131(3):034906. doi: 10.1063/1.3179683.
The growth sequence of gas-phase cholesterol clusters (Ch(N)) with up to N=36 molecules has been investigated by atomistic simulation based on an empirical force field model. The results of long annealings from high temperature show that the geometric motifs characterizing the structure of pure cholesterol crystals already appear in nanometric aggregates. In all clusters molecules tend to align along a common direction. For cluster sizes above the smallest ones, dispersion interactions among the hydrocarbon body and tails of cholesterol cooperate with hydrogen bonding to give rise to a bilayer structure. Analysis of snapshots from the annealing shows that the condensation of hydrogen bonds into a connected network of rings and chains is an important step in the self-organization of cholesterol clusters. The effect of solvation on the equilibrium properties of medium-size aggregates is investigated by short molecular dynamics simulations for the N=30 and N=40 clusters in water at near ambient conditions and in supercritical carbon dioxide at T=400 K.
基于经验力场模型，通过原子模拟研究了气相胆固醇簇（Ch(N)）（N最大为36个分子）的生长序列。高温长时间退火的结果表明，表征纯胆固醇晶体结构的几何基序已出现在纳米聚集体中。在所有簇中，分子倾向于沿共同方向排列。对于大于最小尺寸的簇，胆固醇的烃基主体和尾部之间的色散相互作用与氢键协同作用，形成双层结构。对退火过程中快照的分析表明，氢键凝聚成相互连接的环和链网络是胆固醇簇自组装的重要步骤。通过在接近环境条件的水中以及在T = 400 K的超临界二氧化碳中对N = 30和N = 40的簇进行短分子动力学模拟，研究了溶剂化对中等尺寸聚集体平衡性质的影响。
