Structure of styrene molecular lines on Si(100)-(2x1):H

First-principles electronic structure calculations have been used to study the structure of styrene lines on H-covered Si(100). The predicted structures are less symmetric than the close-packed, parallel-ring structure that has been inferred from STM images, and the results suggest other possibilities that should be considered. In particular, the rings at chain ends are likely to be fluxional, favoring structures with rings that are perpendicular to the other rings in the row. The charge state of the dangling bond at the chain end does not affect the favored orientation of the rings, and the structure at the H-terminated end of the line is not different from that at the end with the dangling bond. Comparisons are made among predictions with different cluster models, different electronic structure methods (DFT and MP2), and different basis sets.