Vibrational properties of the Si(100)2×1 surface

The vibrational properties of the reconstructed Si(100)2×{}1 surface have been studied using a Keating model and a dimer-bond description of the reconstructed surface. This model is sufficiently flexible that the effects of variations in surface geometry and force constants can be examined easily. Calculations have been made of the on-site and the intersite vibrational correlation functions and also of the wave-vector-dependent eigenstates which are localized in the surface region. The calculations were performed using a technique which involves Fourier transforming the dynamical matrix parallel to the surface and making recursion calculations perpendicular to it. Calculations were made for varying surface dimer force constants and tilt angle. A number of interesting modes have been found to be localized in the surface region, and aspects of their features have been related to the surface geometry and bonding. The surface correlation functions exhibit significant anisotropy, temperature dependence, and intersite correlation. The present results are compared with the results of other calculations, and their implications for understanding such experimental data as high-energy ion scattering are discussed.