AlSunaidi A, Lach-Hab M, Gonzalez AE, Blaisten-Barojas E
Institute for Computational Sciences and Informatics, George Mason University, Fairfax, Virginia 22030 and Institue for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Jan;61(1):550-6. doi: 10.1103/physreve.61.550.
The structure and aggregation kinetics of three-dimensional clusters composed of two different monomeric species at three concentrations are thoroughly investigated by means of extensive, large-scale computer simulations. The aggregating monomers have all the same size and occupy the cells of a cubic lattice. Two bonding schemes are considered: (a) the binary diffusion-limited cluster-cluster aggregation (BDLCA) in which only the monomers of different species stick together, and (b) the invading binary diffusion-limited cluster-cluster aggregation (IBDLCA) in which additionally monomers of one of the two species are allowed to bond. In the two schemes, the mixed aggregates display self-similarity with a fractal dimension d(f) that depends on the relative molar fraction of the two species and on concentration. At a given concentration, when this molar fraction is small, d(f) approaches a value close to the reaction-limited cluster-cluster aggregation of one-component systems, and when the molar fraction is 0.5, d(f) becomes close to the value of the diffusion-limited cluster-cluster aggregation model. The crossover between these two regimes is due to a time-decreasing reaction probability between colliding particles, particularly at small molar fractions. Several dynamical quantities are studied as a function of time. The number of clusters and the weight-average cluster size display a power-law behavior only at small concentrations. The dynamical exponents are obtained for molar fractions above 0.3 but not at or below 0.2, indicating the presence of a critical transition between a gelling to a nongelling system. The cluster-size distribution function presents scaling for molar fractions larger than 0.2.
通过广泛的大规模计算机模拟，对由三种浓度的两种不同单体物种组成的三维簇的结构和聚集动力学进行了深入研究。聚集的单体具有相同的大小，并占据立方晶格的晶格点。考虑了两种键合方案：（a）二元扩散限制簇 - 簇聚集（BDLCA），其中只有不同物种的单体粘在一起；（b）侵入性二元扩散限制簇 - 簇聚集（IBDLCA），其中另外允许两种物种之一的单体键合。在这两种方案中，混合聚集体表现出自相似性，其分形维数d(f)取决于两种物种的相对摩尔分数和浓度。在给定浓度下，当该摩尔分数较小时，d(f)接近单组分系统反应限制簇 - 簇聚集的值，当摩尔分数为0.5时，d(f)接近扩散限制簇 - 簇聚集模型的值。这两种状态之间的转变是由于碰撞粒子之间反应概率随时间降低，特别是在小摩尔分数时。研究了几个动力学量随时间的变化。簇的数量和重均簇尺寸仅在低浓度下表现出幂律行为。对于摩尔分数高于0.3时获得了动力学指数，但在0.2及以下时未获得，这表明在凝胶化系统和非凝胶化系统之间存在临界转变。簇尺寸分布函数对于摩尔分数大于0.2时呈现标度关系。
