Molecular dynamics simulation of adsorption processes on the surface of ZnO nanoclusters

This work carried out research of the adsorption processes of O2 molecules on ZnO nanoclusters under different initial conditions by molecular dynamics method. To describe the interaction between atoms, we used the reactive force field (ReaxFF) interatomic potential. Several computer experiments were conducted with different initial conditions. We have been found that the whole process of adsorption was divided into two stages, the first stage was characterized by a rapid increase in the number of adsorbed molecules, the second one an increase of fluctuations in the change of adsorbed molecules on the surface over time. The higher gas pressure in the system corresponds to the greater number of O2 molecules diffusing into the volume of the ZnO nanocluster, therefore, the crystal structure of the surface of the ZnO nanocluster becomes amorphous. In addition, it was established that the tendencies of distribution of the dependence of the central symmetry parameter with the oxygen concentration in the system (NO2 < 100 molecules) were similar. The situation was quite different when the number of oxygen molecules increased: the value of the central symmetry parameter of surface atoms was more evenly distributed, which cannot be considered as a crystalline state of ZnO nanocluster.