LEED evaluation of three models of the Si{100} surface

Abstract A strong body of opinion has recently favoured the buckled dimer type of model for the Si{100} surface and we compare LEED calculations for two such models with experiment. The first model is that of Yin and Cohen which was proposed on the basis of minimization of the Hellman-Feynman forces using a self-consistent, local density, pseudopotential theory. The second model is that of Yang, Jona and Marcus which was found by varying structural parameters to obtain agreement with the LEED data. For comparison we also include the symmetric dimer model of Tong and Maldonado. Our calculations are fully dynamical and we treat the actual structures proposed without imposing any limitations to aid computation. We present visual comparisons of calculations and experimental data and also calculate the Pendry R factors. We find that the Yang, Jona and Marcus model is in best agreement with experiment, but the improvement over the other two models does not seem to be as great as one might expect if the structure were essentially correct. There is still some question therefore as to whether the model needs only minor modifications or significant changes.