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The ITAP Molecular Dynamics Program

Scientific area

Classical molecular dynamics simulations.

Short description

IMD is a software package for classical molecular dynamics simulations. Several types of interactions are supported, such as central pair potentials, EAM potentials for metals, Stillinger-Weber and Tersoff potentials for covalent systems, and Gay-Berne potentials for liquid crystals. A rich choice of simulation options is available, e.g. different integrators for simulations of various thermodynamic ensembles or options that allow to shear and deform the sample during the simulation.

The main design goals were to create a flexible and modular software reaching high performance on contemporary computer architectures, while ensuring portability. IMD runs efficiently on both single processor workstations and massively parallel supercomputers. The parallelization uses the standard MPI library for message passing. As IMD is written in ANSI C, it is portable to any Unix-like environment.

DeformationDeformation of an aluminum sample consisting of over 200 million atoms. On the left hand side, atoms are removed and instead the dislocation structure induced by the deformation is shown.


  • 458,752 cores (1,835,008 parallel MPI tasks) on BlueGene/Q
  • 131,072 cores on x86 (Jaguar)

Weak scaling of IMD on JUQUEENWeak scaling test using IMD with an embedding energy potential on JUQUEEN. Excellent efficiency on the full machine is achieved using at least 2000 atoms per MPI process (64 MPI processes per node). Simulations using fewer particles are limited by communication.

Programming language and model

  • C
  • MPI, OpenMP

Tested on platforms

  • BlueGene/Q, /P and /L
  • x86
  • Cray T3E

Application developers

Institut für Theoretische und Angewandte Physik
Universität Stuttgart


High Performance Computing in Materials Science
Ruhr-Universität Bochum
44801 Bochum

Simulation Laboratory Molecular Systems
Jülich Supercomputing Centre
Forschungszentrum Jülich GmbH
52425 Jülich

(Text and images provided by the Simulation Laboratory Molecular Systems)