First-principles Calculation Of Several Metal Step Barriers

In the past decade,driven by the potential application of metal thin films and metal nanorods,metal growth has become an important part of experimental and theoretical research.The research on the metal growth process found that the step barrier plays an extremely important role in the growth of metal films and nanorods.In particular,the change in the number of steps from a single layer to multiple layers can cause changes in the morphology of the metal film and nanorods during the growth process.This indicates that the growth of metal thin films and nanorods can be controlled by controlling the step barrier.It is precisely to achieve this goal that the research on step barriers has received extensive attention and attention.Initially,in order to theoretically study the diffusion barriers of several metals on the steps,this paper uses the method of combining first-principles calculation based on density functional theory with CI-NEB.And before the calculation,through the existing calculation results to understand the calculation of the metal(111)step barrier.For example,on the Cu(111)plane,there are <110> / {111} type A steps and <110> / {100} type B steps.When a single Cu diffusion atom diffuses on these two types of steps,diffusion will occur through the exchange mechanism or the jump mechanism.As the number of layers of these two types of steps changes from single layer to multi-layer,the step barrier will also change from a two-dimensional step barrier to a three-dimensional step barrier.Furthermore,in order to obtain the step barriers of several metals,the VASP software package used in this paper first optimizes the lattice constants of several metals,and the lattice constant of Al metal is 4.049 ?,and the lattice of Ag metal is 4.149 ?,and the lattice constant of Pt metal is 3.967 ?.Then,we use the optimized lattice parameters to construct the atomic configuration of Al(111),Ag(111)and Pt(111)plane steps.Additionally,considering that a single metal diffusion atom will diffuse from the fcc site or hcp site on the metal(111)surface through the A-type step or the B-type step to a lower atomic layer,so in this paper we calculated the step barriers of an adatom diffusion on those different paths.Because there are also two kinds of diffusion mechanisms when an adatom downward diffusion,so in this paper,the two diffusion mechanisms are involved in calculating the Al(111)step barrier,but on Ag(111)and Pt(111)the calculation of the step barrier only involves the exchange mechanism.Finally,through the simulation calculation of the above-mentioned metal step barriers,through the exchange mechanism,on the aluminum(111)surface,the 2D ES barrier and the 3D ES barrier for the A-type step are 0.069 e V and 0.15 e V,the 2D ES barrier and 3D ES barrier for the B-type step are 0.07 e V and 0.31 e V,respectively.On the silver(111)surface,the 2D ES barrier and the 3D ES barrier for the A-type step are 0.326 e V and 0.24 e V,and the 2D ES barrier and 3D ES barrier for the B-type step are 0.159 e V and 0.339 e V.On the platinum(111)surface,the 2D ES barrier and the 3D ES barrier for the A-type step are 0.39 e V and 0.35 e V,and the 2D ES barrier and 3D ES barrier for the B-type step are 0.80 e V and 0.97 e V.