title: Two dissociation pathways of water and ammonia on the Si(001) surface.
abstract: Using first-principles density-functional calculations, we investigated two competing pathways for the dissociation of water and ammonia on a Si(001) surface. For both systems, we found that, in addition to the conventionally accepted intradimer transfer of the H atom, the interdimer transfer of the H atom can be equally probable with the same reaction mechanism. Our analysis shows that the two dissociation pathways occur through the Lewis acid-base reaction between the partially positive H ion and the electron-abundant up atom of the buckled Si dimer. The result of the interdimer H transfer not only supports a recently proposed model for C-defect on Si(001) but also corresponds to the recent scanning tunneling microscopy data of ammonia dissociation on Si(001).
authors.affiliation: Quantum Photonic Science Research Center, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.
authors.forename: Jung-Yup
authors.initials: JY
authors.lastname: Lee
authors.forename: Jun-Hyung
authors.initials: JH
authors.lastname: Cho