1、A brief introduction to simulation and visualization software LAMMPS、OVITO 2017.10.20,1、Introduction to molecular dynamics. 2、What is Lammps? 3、Commands of Lammps. 4、How to use visualization softwareOVITO?,Report content,Atomic diffusion Surface, interface, defect Crystal growth, Solid phase transit

2、ion Melting, solidification, amorphous formation Mechanical properties Phonon, thermodynamic properties,1.The application of MD,Report content,2. MD Potential function,Pair potential : Lennard-Jones、Morse,Multiple body potential,EAM、Finnis-Sinclair, Extended FS SMA-TB、Smoothed SMA-TB Johnson、Mishin、

3、Zhou ,Consider the angle effect,MEAM / 2NN-MEAM Stillinger-Weber、Tersoff Bond-Order potential,二、Lammps軟件的基本介紹,Lammps？,Large-scale Atomic/Molecular Massively Parallel Simulator,Advantage： Free open source code; can be modified according to need to expand the calculation process （C+） Simulate the soli

4、d, liquid, gas state Simulate millions of particles Convenient parallel computing,Atomic creation ： (Command ：read_data, lattice, create-atoms, delete, replicate) Read the atom from the file Creates an atom in one or more lattices Delete, copy, replace,Output ： (Command ：dump, restart) The position,

5、 speed, acceleration, energy, pressure of the atom,4. LAMMPS example,Simulation of Solidification of Cu by EAM Potential Cu： Lattice structure ：FCC，4 atoms / cell Lattice constant ：3.615 Construct 6 6 6 supercell cells , 864 atoms， lx = ly = lz = 21.69 ,Visualization of Atomic Structures ：Ovito,Ovit

6、o interface,輸出數(shù)據(jù)文件,Step Temperature Potential energy Total energy Pressure Volume,Script file,Calculation result analysis,Glass transition temperature ：Tg 1000 K,eV/atom J/mol,p0, H = U+pV U,Mean square displacement(MSD):,For binary alloys, the self-diffusion coefficient DA and DB are obtained from the slope of the MSD. According to Darkens law, the interdiffusion coefficient is ：Dalloy = xBDA + xADB,PDF:,The second peak splits into two peaks, usually a sign of amorphous formation,Simulation process ：,Enter the file Run Output results Visualization Result analysis,La