Scanning tunnelling microscopy (STM) is a powerful technique for imaging and manipulating surface structure on an atomic scale and is finding novel applications in nano-scale technology. An accurate description of the surface potential barrier is essential for a detailed understanding of STM and related surface spectroscopies. At present such a description does not exist.
We propose to apply a new approach based on quantum Monte Carlo to the above problem.
Our aim is to adapt the quantum Monte Carlo methods developed in the host group to surface geometries and perform full many-body calculations of the surface barrier of Si and A1, and the tunnelling barrier between a metallic tip and the A1(111) surface. We intend to investigate, from the first-principles, the effect of the three-dimensional barrier on tunnelling currents in STM.