Cooperative Chiral Adsorption of Styrene Molecules on the Si(001)-c(2 x 4) Surface: First-Principles Investigation of Reaction Mechanisms

摘要

Detailed reaction mechanisms for the chiral adsorption of styrene molecules on the reconstructed Si-(00l)-c(2 x 4) surface are investigated using first principles calculations based on density functional theory. The most stable configuration corresponds to the R chirality on the so-called "on-top" site, where the molecule is adsorbed on a single silicon dimer. The on-top styrene adsorption does not encounter reaction barriers, but there is a small energy barrier following an intermediate metastable state associated with the styrene adsorption on bridge sites between two Si dimers (the "single-end-bridge" site, or SEB). Our calculations show that when thefirst styrene molecule is adsorbed in the SEB configuration, there is no energy barrier associated with the adsorption of the second molecule. This cooperative effect leads to the experimentally observed "paired end-bridge" configuration.