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IMD - The ITAP Molecular Dynamics Program

IMD is a program package for classical molecular dynamics simulations, which has originally been implemented by Jörg Stadler at ITAP. Since then, it has been extended in various ways, and is still continuously developed. IMD runs both on normal Unix workstations of any kind, as well as on massively parallel supercomputers, such as the Cray T3E at HLRS. The parallel version is built upon the standard message passing library MPI, which is used for the communication between processors.

In a molecular dynamics simulation, Hamilton's equations for a system of interactiong particles are integrated numerically. IMD supports the following types of interactions: tabulated two-body potentials, EAM potentials for metals, Stillinger-Weber and Tersoff potentials for covalent systems, and Gay-Berne potentials for linear molecules, like the ones needed for the simulation of liquid crystals. A large choice of different integrators is at the user's disposal. Besides the usual ones, which keep energy and volume, temperature and volume, or temperature and pressure constant, there are also more specialized ones, which allow, e.g., to put the sample under tension or shear stress. These are used to study the mechanical properties of the system, such as dislocation motion or crack propagation. The integrator can also be changed during the simulation (multiphase simulation).

There is a user guide available, which explains all the different options of IMD.