On the concept and distribution of reactive sites in dissociative chemisorption

摘要

We present results of classical stochastic molecular dynamics simulations of dissociative chemisorption in two different model systems, H2/Ni(100) and N2/W(110). Based upon the separation of time scales between dissociation and translations and rotations, we determine: (1) the location of the dissociation within the unit cell of the surface and (2) the orientation of the molecule at the time of dissociation. The two systems displayed opposite and unusual behavior with the former exhibiting site selectivity even thoughS0ape;0.8 and the latter exhibiting nonsite selectivity forS0ape;0.13. This behavior is explained in terms of the characteristics of the moleculendash;surface and atomndash;surface interaction potentials and the general strength of adsorbatehyphen;surface vs surfacendash;surface bonds.