|
Since its invention scanning tunnelling microscopes have rapidly become the key instrument not only for the atomic scale analysis of surfaces, interfaces, and molecular structures, the instrument’s resolution has made it increasingly possible to detect electronic processes which before remained elusive. Driven by experimental advances sophisticated theoretical techniques have been developed, which make direct comparisons with quantitative results a close to routine procedure. The key ingredient in these techniques is the inclusion the STM tip in the simulations, and the use of highly accurate electronic structure methods. We provide several examples of the present state of theory, ranging from traditional problems of adsorption and catalysis1, single adatom properties2, to new magnetic structures, organic interfaces, and semiconductors3. Particular emphasis shall be placed on functionalising interfaces and molecular structures, which can be analyzed in great detail by STM4,5. Additionally, we discuss the existing limitations due to numerical constraints in the underlying density functional theory. Finally, we point out how the material characteristics of the STM tip may be optimised to yield an equally high performance not only in topographic scans, but also in spectroscopic measurements.
[1] F Calleja et al. Phys. Rev. Lett. 92, 206101 (2004)
[2] L. Limot et al. Phys. Rev. Lett. 94, 126102 (2005)
[3] L. Zotti, W. A. Hofer and F. Giessibl, Chem. Phys. Lett. 420, 177 (2006)
[4] P. Piva et al., Nature 435, 658 (2005)
[5] S. Dobrin et al., Surf. Sci. Lett. 600, L43 (2006)
[6] Z. T. Deng et al., Phys. Rev. Lett. 96, 156102 (2006)
|