SIMULATION OF LOCAL SURFACE MODIFICATION IN STM BY AB-INITIO QUANTUM-CHEMISTRY

Surface modification by means of STM has became a well-known method fo r the artificial formation of nanometer and atomic scale structures. T he physical nature of surface modification can consist in a wide range of phenomena (from mechanical indentation up to specific tip-induced chemistry). The high electrical field at the STM tip is considered to be the main feature of STM modification experiments. The field strengt h is comparable with Intramolecular ones and can influence the chemica l bonding in surface structures. The model of STM-stimulated modificat ion is considered using the quantum-chemical ab initio approach for a surface cluster in the high electrical field. The destabilization effe ct, energy level shift, and bond polarization under the STM tip field occur and can show the atomistic nature of surface transformations in STM.