F-MD, Fortran Molecular Dynamic

A simple Molecular Dynamic implementation in Fortran.

Molecules are randomly initialized in a simulation box with Periodic Bondary Condition using minimal image. Lennard-Jones force are then propagated along the time using a Velocity Verlet integrator.

Installation

To install, clone this repository:

git clone git@github.com:comecattin/F-MD.git
cd F-MD

Then compile the source:

cd src
make

Run an MD simulation

To run an MD simulation simply run ./md_simulation input.in in the src directory.

The file input.in is the input file and contain:

• The number of particles (n_atoms, default 30)
• The number of time steps (n_steps, default 1000)
• The time step (dt, default 0.001)
• The box length (box_length, default 10.0)
• The tolerance of the SHAKE algorithm for angle and bonds length constraints (tolerance, default 1e-6)
• The maximum number of iteration for the SHAKE algorithm (max_iter, default 100)

An example is given in the examples/example_input.in file.

Output and plot the trajectories

By default, positions along time steps are outputted in the trajectories.dat file.

To plot an animation of the trajectories, run python plot_trajectories.py in the directory where the trajectories.dat file is written.

Output and plot the energies

Kinetic, potential and total energies are by default computed at each time step and saved under the energies.dat file.

To plot theses energies along the time, run python plot_energies.py energies.dat. An energies.pdf file will be written.