Disclaimer: this repository contains the files for a homework assignment for a computational physics class in 2016. The LAMMPS input files might no longer be up to date with the current release of LAMMPS.

Preparation

1. Install lammps (with the USER-REAXC package), consult the manual of lammps for instructions
2. Install vmd (visual molecular dynamics)
3. Have a look at the manual of lammps
4. Have a quick look at all the files in this repository
5. For python users: have a look at the log.py tool from the pizza.py module.

Tasks

1. Use 'graphene.m' to create a small graphene sheet (only a single rectangular cell with 4 atoms is enough). Study briefly the format of the output file. You can read about the data format in the manual (see command 'read_data').
2. Study the input script 'profile.lmp'. Consult the manual if commands are not clear. Use this script to plot the energy in function of the distance between the carbon atoms. What is the interatomic distance for a relaxed graphene sheet? (Tip: start with an interatomic distance of 1A).
3. Use 'graphene.m' to create a large relaxed graphene sheet with at least 200 atoms. Use 'tensiletest.lmp' to obtain the stress/strain curve. Determine the Young's modulus and the breaking stress/strain. Stretch in x and y direction. Which effect has the temperature on the breaking stress/strain? Check how computational parameters influence the simulation.
4. Study the buckling of graphene under compression. This can be done with 'tensiletest.lmp'. Check how computational parameters influence the simulation.
5. Use 'melting.lmp' to determine the melting temperature of graphene. Check how computational parameters influence the simulation.
6. Redo task 3,4 and 5 for silicene. Use the reaxFF parameters of Si in 'ffield.reax.CHONSSi.2' and the silicene sheet defined in 'silicene.dat'. Make a comparison of the results for graphene and silicene.