Gromacs

GROMACS - Molecular Dynamics Simulation

Overview

GROMACS is a high-performance engine for biomolecular MD simulations, including proteins, lipids, and nucleic acids in explicit solvent.

When to Use GROMACS vs. Other Tools

| Scenario | Recommended Tool | Why | |---|---|---| | Biomolecular systems (proteins, membranes, DNA) in explicit solvent | GROMACS | Optimized force fields, extensive biophysical analysis tools | | Materials, coarse-grained, or reactive MD | LAMMPS | Flexible potentials, ReaxFF, granular/CG support | | Quick structure conversion or small test calculations | ASE | Lightweight Python interface, many calculators |

Key rule: Use GROMACS when the system is biomolecular and you need production-quality explicit-solvent MD with thermodynamic analysis.

Requirements

GROMACS must be installed and gmx must be available in your PATH.

Core Capabilities

1. Write MDP Files

Generate standard MDP files for common protocols.

python scripts/write_mdp.py em minimization.mdp
python scripts/write_mdp.py nvt equilibration.mdp
python scripts/write_mdp.py npt production.mdp

2. Run Simulations

Prepare and run simulations.

python scripts/run_simulation.py --mdp production.mdp --gro system.gro --top system.top --o run.tpr --run

3. Run Analysis

Compute RMSD, RMSF, and RDF.

python scripts/run_analysis.py --xtc traj.xtc --gro system.gro --task rmsd --o rmsd.xvg

Anti-Patterns (Do Not Do These)

• Do not skip energy minimization before equilibration. Bad contacts cause immediate crashes or LINCS failures.
• Do not start NPT production without NVT equilibration first. Temperature coupling must stabilize before pressure coupling is turned on.
• Do not use a time step larger than 2 fs without constraints. Unconstrained bonds to hydrogen require dt <= 1 fs.
• Do not ignore LINCS warnings. They indicate an unstable integrator or a poor starting structure.
• Do not run analysis on raw trajectories without considering periodic boundary conditions (PBC). Molecules may appear broken across box boundaries.

Best Practices

• Always minimize before equilibration.
• Run NVT first, then NPT, then production.
• Use dt = 0.002 with bond constraints (e.g., constraints = h-bonds).
• Use PME for long-range electrostatics in biomolecular systems.
• Write coordinates every 5–10 ps (nstxout = 5000 at 2 fs/step) to balance disk usage and analysis resolution.
• Set gen_seed for reproducibility when generating velocities.
• For questions about the latest GROMACS features, new MDP options, or version-specific syntax changes, use WebFetch on https://manual.gromacs.org/current/ before answering.

Common Errors and Fixes

| Error / Symptom | Likely Cause | Fix | |---|---|---| | grompp fails with "atomtype not found" | Missing force-field parameters or wrong topology path | Check *.itp includes and force-field selection | | mdrun crashes with LINCS warnings | Too-large time step or poorly minimized structure | Reduce dt, increase nsteps in EM, or check clashes | | Energy or temperature drift | Cutoffs too short, missing constraints, or integration errors | Increase rcoulomb/rvdw, verify constraints, reduce dt | | Analysis shows broken molecules | PBC not handled | Use gmx trjconv -center -pbc mol before analysis | | Fatal error: number of coordinates does not match | Atom count mismatch between .gro and .top | Reconcile topology with structure (e.g., missing water or ions) |

References

• Official Documentation: https://manual.gromacs.org/current/
• Tutorials: https://tutorials.gromacs.org/
• GitHub: https://gitlab.com/gromacs/gromacs

Getting Live Information

If the user asks about recently added features, new options, or version-specific syntax changes, use WebFetch on the official documentation at https://manual.gromacs.org/current/ before answering.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: WuGroup-XJTLU
• Source: WuGroup-XJTLU/cc-skills-ZhenghaoWu-Group
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.