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CPM Seminar
ab initio simulations as a guide to interpretation Werner A. Hofer
Dept. of Physics and Astronomy We have developed a robust and computationally efficient method to simulate STM topographies and spectroscopies on crystal surfaces. The method is based on first principles density functional theory and a perturbation approach to tunneling. It can be used for metals, semiconductors, and molecular structures on semiconductors with the same accuracy. The computed results, position and distance dependent current maps in terms of sample bias, allow in most cases (a) the identification of surface atoms, and (b) the identification of the STM tip apex. The method is discussed in relation with several trial systems: PtX(100) alloys, Fe(100), and benzene and acetylene molecules on Si(100). We give a critical assessment of the method and a limit of its applicability, mainly due to the breakdown of perturbation theory in the low distance range.
Thursday, September 28th 2000, 15:30 |