Accuracy of trajectory methods for activated adsorption of H2 on Cu(100)

We perform classical and quasiclassical trajectory calculations for the dissociative adsorption of normally-incident (v=0, j=0) H2 on Cu(100). A direct comparison is made between the trajectory results and previously obtained (6D) quantum wave packet results for the same potential energy surface [which is a fit to points calculated from density functional theory (DFT)]. The quasiclassical reaction probability is in much better agreement with the quantum probability than the classical. Quasiclassical calculations for two (v=0, j=4, mj) incident states also give good agreement with the quantum reaction probabilities, suggesting that the method may be used for computing alignment of H2 in desorption.