Elucidation and Control of Surface Electronic and Atomic Processes by the Tip

Various phenomena are induced by the nano-scale gap between the tip and the sample surface in thescanning probe microscopy. Among them the elementaly processes of electrons and atoms are mostimportant both for the fundamental science and for the基础理论应用。purpose of this projet is to develop a theoretical method to describe and predics这些processesand clarify their fundamental aspects. For that purpose the first principles recursiontransfermatrix method is developped which is an extension of the Density功能理论non-equilibrium open systems. In this method wavefunctions are solved In a scattering wave forms andthe tunneling tails are very precisely determined. With the方法quntitative analyzes of STM，tip工业化学过程atom transfer between the tip and over the surface can be studied from the first principles.Withthis method the following problems are studied. the first is the microscopic contact between the twoA sharp onset of the electronic inceraction of sufaces is found and the details of thepotential distribution are studied as well as the concept of the local workiunction.The mechanism ofatom extraction by the tip of STM is clarified as follows. When the tip is negatively biasedthe electron cloud is pushed cut in front of the tip apex.那么它是accumlated in the interstitial区域between the tip apex atom and the surface atom confronted to it. With the further increaseof the negative tip bias, the electron cloud forms a bridge structure with the surface这是一个非常强大的force is acted on the suriace atom. the situationis quite dependent on the tipheight and the tip surface materials。

Various phenomena are induced by the nano-scale gap between the tip and the sample surface in the scanning probe microscopy. Among them the elementaly processes of electrons and atoms are most important both for the fundamental science and for the basis of thechnological applications. The purpose of this projet is to develop a theoretical method to describe and predics these processes and clarify their fundamental aspects. For that purpose the first・principles recursiontransfer matrix method is developped which is an extension of the Density Functional Theory for non-equilibrium open systems. In this method wavefunctions are solved in a scattering wave forms and the tunneling tails are very precisely determined. With the method quntitative analyzes of STM,tip induced chemical processes, atom transfer between the tip and over the surface can be studied from the first・principles.With this method the following problems are studied. The first is the microscopic contact between the two surfaces. A sharp onset of the electronic inceraction of sufaces is found and the details of the potential distribution are studied as well as the concept of the local workiunction.The mechanism of atom extraction by the tip of STM is clarified as follows. When the tip is negatively biased, the electron cloud is pushed cut in front of the tip apex. Then it is accumlated in the interstitial region between the tip apex atom and the surface atom confronted to it. With the further increase of the negative tip bias, the electron cloud forms a bridge structure with the surface, then a very strong force is acted on the suriace atom. The situationis quite dependent on the tip height and the tip surface materials.