Femto-Research

Codes for femtosecond laser interaction research. Note Femto3D does not work in LAMMPS version later than 2021.

If you have any questions, please email yuanweirong78@gmail.com.

Femto3D

This is the modified LAMMPS function based on its two-temperature function. Put fix_femto3D.cpp and fix_femto3D.h in the same folder as fix_ttm_mod.cpp and compile in the same way. Reference: https://docs.lammps.org/fix_ttm.html#fix-ttm-mod-command

Preheating

A target generated in MD is preheated to a wanted temperature and then relaxes to equilibrium. The output file for further use is a LAMMPS restart file for further simulation. The default output from the sample input code is restart.equil.mpiio.

Common Runs

The LAMMPS input file requires a restart file which would be generated from the Preheating LAMMPS codes. The restart file by default should be renamed from restart.equil.mpiio to TTM_restart_0.mpiio.

Au Parameters

Example parameters for Au. They are required for common runs. The units are based on the metal-style of LAMMPS.

Ke: eV / (ps * A * K); Ce: eV / (A^3 * K); G: eV / (A^3 * ps * K).

Analysis

The read.cpp and read2.cpp are to process the dump files from LAMMPS outputs and they should run in order. The rest MATLAB files are to generate figures using the temperature files from LAMMPS and the output files from read.cpp and read2.cpp.

Example commands to run LAMMPS simulations

mpiexec -np 60 PATH/TO/YOUR/lmp_mpi -in Au_TTM_restart.in as in run.sh.

Tips

• It is recommended to run Preheating and Common Runs in seperate folders.
• Use tmux in a remote server for long runs.

Reference

• Paper: Ablation study in gold irradiated by single femtosecond laser pulse with electron temperature dependent interatomic potential and electron–phonon coupling factor