Molecular dynamics example programs in Fortran 90

• md1.f90: A simple molecular dynamics programs, using the Lennard-Jones potential. The potential is computed analytically in the force loop. The force loop goes over all the particle pairs. This code is simple but slow.
• md2.f90: As md1, but the potential is stored into numerical tables (once for all, during initialization), and table look-up followed by interpolation are performed in the force loop. This brings little - if any - speed advantage for Lennard-Jones, but allows to deal efficiently with other potentials, such as those including trascendental functions in their definition, or with those which are just given in a numerical form.
• md3.f90: As md2, but with Verlet neighbor lists. Automatic list update, based on the amplitude of the displacement of individual particles since the last list formation. The program operation depends on the skin parameter which can be tuned to optimize CPU time.
• md3glue.f90: As md3, but for a many-body "glue" potential instead of the Lennard-Jones potential. The file aluminum.f, to be compiled and linked with md3glue, contains the functions for the ab initio-derived Al potential of Ercolessi and Adams.

The above programs require a starting configuration containing the atomic positions and velocities. You can generate one such configuration from scratch using crystal.f90, which arranges atoms in an f.c.c. lattice, or use a configuration produced by a previous molecular dynamics run.

See the README file for more detailed information.

Here are some exercises you can do with these codes.

Suggestions and/or bug reports are welcome.

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