Simulating Research Of Nano-structure's Properties Based On Atomistix ToolKit (ATK)

This paper adopts the way of computer simulation to simulate nano-structure, and further studies the physical properties of nano-structure.The software used by this paper is ATK and VNL which are developed by Atomistix company,and according to the first principle simulates nano-systems,electrical properties and quantum transport properties of nano-device.This paper introduces basic knowledge of nano-system and effects and properties of material in nano-scale fielde,and then describes the advantage of computer simulation,unique features of ATK and basic knowledge of VNL.Finally, it introduces NanoLanguage,especially Python's features,functions and editting script.By running script with different function which is editted by user,ATK simulates nano-structure.The key of editting script is to define parameter,test and select proper value,and to save the input file in format of atk(filename.atk),at the same time marking the output file—NetCDF format(filename.nc)in input file. Calculated results of ATK can be visualized in any proper graphical program,here useing VNL.However,VNL is not only a visualized program,but also is a numerical calculation program to execute simulation,and VNL can simulate calculation directly.In visualizion and calculation,combining ATK and VNL,structures of molecular system,crystal system and two-probe system are simulated,and molecular orbits,electronic density,Bloch function and bands structure are analyzed.By testing and simulating,the paper calcalates bond length and bond energy of H₂,and comparing with results of other method and theoretic value;in order to verify applicability of DFT,the paper calculates bond length of some molecules of double atoms:F₂,HF,Cl₂ and O₂.By analysing a series of simple molecular structures,simulation of ATK and VNL on H₂ molecule is not good,but on other molecules(except H₂)well.The reason is that DFT method is not suitable to discribe the weak interaction system as force of van der Waals,and gradient modification method just considers pure exclusive interaction,and for hydrogen bond,force is mainly electrostatic force,so simulation of DFT method is impossibly very accurate.