Theoretical Study On Transverse Atomic Maneuvering Of Metal Fcc (001) Surface Temperature

Single atom manipulation has attracted enormous attention in recent years because of its promising applications in nanofabrication and nanoengineering. Due to the requirement of the thermal and mechanical stability, manipulations are usually carried out under cryogenic environment and can be successful only on the surfaces with weak atom-substrate interactions if without other assistant methods, e.g., applying extra electronic or magnetic field. Experimental and theoretical studies of atom manipulation at room or higher temperature, which aims to the manipulation on the strong atom-substrate metal fcc(001) systems, have seldom been reported up to now. In present work, we investigate the lateral atom manipulation with thermal assistant method at elevated temperatures on silver and platinum fcc(001) surfaces. Simulations and calculations using molecular dynamics and statics methods finally enable us to see clearly the influential factors in the reliability during the manipulation at elevated temperature, by which we can obtain reliable lateral atom manipulation under proper conditions.Chapter 1 provides historical background and new developments of single atom manipulation and raises some important problems that deserve further studies. Chapter 2 describes briefly the theoretical foundations and methods used in the molecular dynamic simulations. We also give the forms of potentials and parameters employed in our study, including surface embedded atom method (SEAM) potentials, the algorithm of solving dynamic equations, the time step and boundary conditions.In chapter 3, we mainly study the successful probability of the lateral manipulation of a single Ag adatom on the Ag(001) surface with single-atom apex tip at elevated temperatures, using both molecular dynamics and molecular statics methods. We have tested and verified the feasibility of thermal assistant methods used in our study and obtained promising probability of successful manipulation under proper conditions. The influences of the tip height, the direction of manipulation and system temperature on the results are examined. In the last part of this chapter we also check the applicability of this lateral manipulation with thermal assistant method on the platinum fcc(001) surface. The result also agrees well with our former expectations, and predicts this method can be generally applied on other surfaces if given proper conditions.The last chapter presents a summary of this thesis and some prospects for the on-going investigations.