Gromacs

Gromacs simulates the Newtonian equations of motion for molecular systems to enable molecular dynamics studies of biochemical molecules such as proteins, lipids, and nucleic acids.

Key Features:

• Force field support: Supports GROMOS, OPLS, AMBER, and ENCAD force fields and can handle polarizable shell models.
• Integration and time-step enhancements: Implements virtual site algorithms that permit larger integration time steps up to 5 fs in atomistic simulations.
• Constraint handling: Provides flexible constraints and a state-of-the-art parallel constraint solver for constrained dynamics.
• Nonbonded interaction performance: Optimized for rapid calculation of nonbonded interactions through algorithmic and hand-coded optimizations.
• Parallelization and hardware acceleration: Leverages SIMD, multithreading, MPI-based parallelism, and GPU acceleration to scale from workstations to HPC clusters.
• Domain decomposition and load balancing: Uses a minimal-communication domain decomposition algorithm with dynamic load balancing for scalable parallel runs.
• Custom forces and tabulated functions: Allows addition of custom force routines and user-specified tabulated interaction functions.
• Nonequilibrium and free-energy methods: Implements nonequilibrium dynamics and free-energy determination algorithms, including newer free-energy algorithms and implicit solvent models.
• QM/MM interfaces: Interfaces MM calculations with quantum-chemical packages such as MOPAC, GAMES-UK, and GAUSSIAN for mixed MM/QM simulations.
• Analysis utilities: Includes a large suite of utility and analysis programs for trajectory and property analysis.

Scientific Applications:

• Protein dynamics: Simulation of protein structural dynamics and conformational changes.
• Nucleic acid simulations: Modeling dynamics and interactions of DNA and RNA.
• Lipid and membrane studies: Simulations of lipids and lipid bilayers, including membrane-associated processes.
• Polymer and non-biological systems: Modeling of polymers and other non-biological condensed-matter systems.
• Free-energy calculations: Alchemical and other free-energy determinations for binding, solvation, and conformational equilibria.
• Nonequilibrium processes: Simulation of driven or time-dependent processes using nonequilibrium dynamics methods.
• QM/MM studies: Hybrid molecular mechanics/quantum chemistry simulations via interfaces to MOPAC, GAMES-UK, and GAUSSIAN.
• High-throughput and large-scale simulations: Production of large trajectories on massively parallel and GPU-accelerated systems.

Methodology:

Integration of Newtonian equations of motion using supported force fields (GROMOS, OPLS, AMBER, ENCAD) with options for polarizable shell models, flexible constraints, virtual sites, custom force/tabulated functions, nonequilibrium and free-energy algorithms, and MM/QM interfacing to MOPAC, GAMES-UK, and GAUSSIAN; performance achieved via SIMD, multithreading, MPI, GPU acceleration, minimal-communication domain decomposition, dynamic load balancing, a parallel constraint solver, and hand-coded algorithmic optimizations.