Reaction Barriers and Cooperative Effects for the Adsorption of Pyridine on Si(100)

The chemisorption of pyridine on Si(100) has been the subject of many studies because the dominant structure identified in experiment is not the most stable structure predicted by theoretical calculations. By first-principles calculations, we have mapped out the reaction paths for all the possible channels starting with the easily formed end-on structure, and further explored the cooperative effects under high coverage. Our results indicate that the relative abundance of various configurations is determined by both temperature and coverage, and the adsorption energy for a configuration could change significantly when the neighboring sites are saturated. With such cooperative effects, it is also possible to form ordered pyridine lines on Si(100).