Dynamics Simulation On Interactions Of Charged Particles With Bent Carbon Nanotubes

Based on the semi-classical dynamics model,it is simulated in this thesis the interactions of moving charged particles(Me V)with single-walled carbon nanotubes(SWCNTs),double-walled carbon nanotubes(DWCNTs),and triple-walled carbon nanotubes(TWCNTs),respectively.The wake effects generated by charged ions interact with SWCNTs and DWCNTs are studied.Besides,the collective excitation effect on the self-energy and stopping power of incident ions are investigated for SWCNTs,DWCNTs and TWCNTs.In addition,by using Thomas-Fermi-Moliere’s continuum potential model to describe the repulsive interaction of charged ions with carbon atoms on the wall,we obtained the total potential of incident charged ions in unbent and bent carbon nanotubes from-calculating the Newtonian equation.The total potential and moving trajectory are also discussed in detail by the influence of different bending angles of carbon nanotubes.By simulation calculations,we found that the induced charge density presents an inverted bell-shaped distribution when the incident ion velocity is lower than the critical value,while a wake effect appears behind the ions when the velocity is greater than the critical value.At the same time,we noticed that compared with SWCNTs,the polarization charges on the inner wall of DWCNTs easily excite the valence electrons on the outer wall,and the degree of excitation of the outer wall is related to the moving speed of incident ions.In addition,from the three-dimensional distribution of the induced potential,we found that the induced potential exhibits an oscillating wake effect in the axial direction,and a maximum value appears on the tube wall.We also found that the existence of the innermost tube and outer tube of three-walled carbon nanotubes has an important influence on the self-energy and stopping power of incident ions,which makes the self-energy and stopping power appear in the low-velocity region with a single-peak or double-peaks structure.Finally,by simulating the interaction between incident ions and bent carbon nanotubes,we found that the bending direction of carbon nanotubes has an effect on the incident ion potential,making the total potential well deeper or shallower,further-affecting the trajectory of the incident ion: when the total potential well is shallower,the incident ions are subject to a greater centrifugal potential,leading to the incident ions move away from the tube wall and close to the central axis of the nanotube,and even move up and down with the central axis of the nanotube as the symmetry axis;when the potential well is deeper,as the bending angle of the carbon nanotube increases,the incident ions move closer to the tube wall,with the amplitude of the helical oscillating trajectories increasing.For DWCNTs,the initial velocity and radius of incident ions have an important influence on the moving trajectory.When the carbon nanotube is bent forward,as the incident velocity and radius of incidence increase,the moving protons move with the central axis of the nanotube as the symmetry axis,and the focusing effect of the carbon nanotube is obvious.The above simulation results provide a certain theoretical basis for the practical applications of unbent and bent carbon nanotubes in the fields of particle transport and ion beam focusing.