Europhys. Lett.
Volume 67, Number 6, September 2004
Page(s) 900 - 906
Section General
Published online 01 September 2004
Europhys. Lett., 67 (6), pp. 900-906 (2004)
DOI: 10.1209/epl/i2004-10143-4

Molecular-dynamics studies of annihilation reactions

F. Baras1, M. Salazar1, E. Kestemont2 and M. Malek Mansour2

1  Laboratoire de Recherches sur la Réactivité des Solides UMR 5613 CNRS-Université de Bourgogne 9 Avenue Alain Savary - BP 47870, F-21078 Dijon Cedex, France
2  Centre for Nonlinear Phenomena and Complex Systems Université Libre de Bruxelles, Campus Plaine - C.P. 231, B-1050 Brussels, Belgium

(Received 14 April 2004; accepted in final form 8 July 2004)

The validity of the reaction-diffusion formulation of annihilation kinetics, with randomly distributed initial conditions, is investigated by molecular-dynamics simulations of dense hard-disk fluids. For the reaction $A+B\rightarrow C+C$ quantitative agreement is found. Yet, this proves not to be the case for the reaction $A+A\rightarrow C+C$, where major discrepancies are observed. For this latter reaction, more sophisticated theories predict a logarithmic decay law of the form $\ln(t)/t$. The microscopic simulations essentially confirm this prediction.

05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
05.90.+m - Other topics in statistical physics, thermodynamics, and nonlinear dynamical systems.
82.20.Wt - Computational modeling; simulation.

© EDP Sciences 2004