The influence of quencher concentration on the excess in the rate of quenching reaction: molecular dynamics study

Molecular dynamics simulations of the reaction A+B → C+B for identical soft spheres in three dimensions have been performed to study the influence of the concentration of B (quencher) on the reaction rate. Many interesting results have been found. For the deterministic systems (liquid and gas), an increase in the quencher concentration decreased the reaction rate coefficient, k(t), in the long-time limit but it increased k(t) at short times. For the Brownian systems the excess in k(t) was positive and, except for very short times, constant. Both for the liquids and the Brownian systems the excess in relative spatial correlations between reagents was strongly correlated with the excess in k(t). The long-time behaviour of the excess in k(t) for the gas was qualitatively similar to that for liquids but the origin of the phenomenon was not the same. For the gas, the excess in k(t) was mainly caused by the excess in the mean radial velocity between A and B, which was completely negligible for the dense liquid and the Brownian system