Pairing and clustering of hydrogen on Si(100)2×1: Monte Carlo studies

Abstract

Pubihc reocrtinrg ourcden fr this ccilecion of information is eitimated to average 1 hour opr reponse. including the time for revewing instruclons. searching extng data wOur(es gather~r'q and rraonta.ng the data needed, and completing and rev eving the ýollectlon of information Send comments regarding this burden estimate Or any other aspect of this colle-mton of ntormaton. nclud ng suggestons for reducing this iourden. to Washington readcltuarters Servies. Directorate for information Operations and Reports. Approved for public release; distribution is unlimited. ABSTRACT (Maximum 200 words)We consider a generalization of the doubly-occupied dimer model we proposed recently to explain the near-first-order desorption kinetics of H2 from Si(100)2xl, incorporating effective nearest-neighbor interactions between paired hydrogen atoms on adjacent dimers. We have performed Monte Carlo simulations of the generalized model, and compare the pairing and cluster-size distributions with those observed recently by scanning tunneling microscopy (STM). The agreement is reasonable but the cluster size distributions differ in shape, which we suggest is due to the nonthermal nature of the distributions observed by STM and/or inadequacies in the use of nearest-neighbor interactions to represent the physics of clustering.Implications of the results for the underlying physical interactions responsible for ordering of hydrogen on Si(100) and for the desorption kinetics are discussed.14. Prexrfbed by ANSI Std Z39-18 296-102Pairing and clustering of hydrogen on Si (100)

Reactions of Nitromethane on Si(100): First-Principles Predictions

“…We have denoted the surface dimer bond as a π-bond, to emphasize the analogy with the corresponding reaction of C−C π-bonds. Of course, the interaction between dimer dangling bonds is quite weak, amounting to less than 10 kcal/mol, − so that the dimer will be much more reactive than a C−C π-bond or even a molecular Si−Si π-bond. The arrows in Scheme indicate formal rearrangement of electron pairs; the charges shown are discussed below.…”