The energetics and dynamics of Si ad-dimers on Si(001) have been investigated by total-energy calculations and scanning tunneling microscopy. Several dimer configurations and a thermally activated rotational mode of the dimer on top of a dimer row are theoretically predicted and experimentally identified. The frequency of occurrence of the different dimer configurations suggests a likely pathway for monomer diffusion.
Zhang, Z., Wu, F., Zandvliet, H. J. W., Poelsema, B., Metiu, H., & Lagally, M. G. (1995). Energetics and dynamics of Si ad-dimers on Si(001). Physical review letters, 74(18), 3644-3647. https://doi.org/10.1103/PhysRevLett.74.3644