Institute of Physical Chemistry, Polish Academy of Science, Warsaw, Poland.
J Chem Phys. 2011 Jun 28;134(24):244505. doi: 10.1063/1.3601343.
We have performed intensive computer simulations of the irreversible annihilation reaction: A + A → C + C and of the trapping reaction: A + B → C + B for a variety of three-dimensional fluids composed of identical spherical particles. We have found a significant difference in the asymptotic behavior of the rate coefficients for these reactions. Both the rate coefficients converge to the same value with time t going to infinity but the convergence rate is different: the O(t(-1/2)) term for the annihilation reaction is higher than the corresponding term for the trapping reaction. The simulation results suggest that ratio of the terms is a universal quantity with the value equal to 2 or slightly above. A model for the annihilation reaction based on the superposition approximation predicts the difference in the O(t(-1/2)) terms, but overestimates the value for the annihilation reaction by about 30%. We have also performed simulations for the dimerization process: A + A → E, where E stands for a dimer. The dimerization decreases the reaction rate due to the decrease in the diffusion constant for A. The effect is successfully predicted by a simple model.
A + A → C + C 和俘获反应：A + B → C + B 在各种由相同球形粒子组成的三维流体中进行了密集的计算机模拟。我们发现这两种反应的速率系数的渐近行为有显著差异。随着时间 t 的增加，两种速率系数都趋近于相同的值，但收敛速度不同：湮灭反应的 O(t(-1/2))项高于俘获反应的相应项。模拟结果表明，该比例项是一个普遍的量，其值等于 2 或略高于 2。基于叠加近似的湮灭反应模型预测了 O(t(-1/2))项的差异，但高估了湮灭反应的值约 30%。我们还对二聚化过程：A + A → E 进行了模拟，其中 E 代表二聚体。由于 A 的扩散常数减小，二聚化降低了反应速率。简单模型成功地预测了这一效应。
