A phenomenon of tip-assisted manipulation in STM became an promising method of nanotechnology for fabrication of nanostructures [1-3].
Its fundamental importance consists in features of processes associated with single clusters rather than usual methods of energy action upon solids when the action is distributed among an extended area of crystal lattice.
Any consistent theory of nanomanipulation is absent at present since elaborate analysis of clusters state and molecules in non-stationary electrical field of STM tip is required. We simulate this task by the quasistationary way considering a state of clusters in the tip field by means of calculation of their electronic structure taking into account polarization of molecular orbitals by tip. The electronic structure of selected cadmium and lead sulfide clusters was calculated at the ab initio level with MOLCAO SCF RHF method for ground states. As far as the similar realistic clusters exist in a stable form (in which they are available for STM experiment [4]) with a protected shell from organic ligands, we consider also the tip field effect upon the stability of the shells and possibility of STM-stimulated aggregation of the clusters.
Thus, quantum chemical calculations of the tip-cluster models show pathways of the reconstruction, chemical bond breaking, and electronic excitation. Formation of new species under STM-stimulated transformations is proposed.
References
[1] Junno T., Deepert K., Montelius L, and Samuelson L. Appl.
Phys. Lett. 66 (1995) 3627.
[2] Cuberes M.T., Schlitter R.R., and Gimzewski J.K. Appl.
Phys. Lett. 69 (1996) 3016.
[3] Ramachandran T.R., Baur C., Bugacov A. et al. 5th Foresight
Conf. Molec. Nanotechnol. (1997).
[4] Erokhin V., Facci R., Carrara S., Nicolini C. J. Phys.
D 28 (1995) 2534.