Agent skill

Force Fields Modeling

by VectorSpaceLab in VectorSpaceLab/AREX-Skill

Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring.

MITAuto-check passed

Install Force Fields Modeling

skills CLI
$ npx skills add VectorSpaceLab/AREX-Skill --skill force-fields-modeling -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install VectorSpaceLab/AREX-Skill force-fields-modeling --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/VectorSpaceLab/AREX-Skill.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/repositories/repo-skills/openmm/sub-skills/force-fields-modeling .claude/skills/force-fields-modeling && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
force-fields-modeling
GitHub stars
328
Token cost
~988 tokens
SKILL.md length
388 words
Files
6 (incl. scripts, references)
Skills in repo
159
Repo updated
First seen
Licence
MIT

At a glance

Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring.

  • Works in 6 steps: Identify whether the inputs are… → Choose force-field XML files as a… → Use Modeller before createSystem() when… → …
  • Working with ForceField.createSystem
  • SKILL.md covers Route Here For, Start With These References, Practical Workflow and Bundled Script, plus 1 more section
  • Runs Python scripts from its folder; calls python

What it does

Force Fields Modeling is an agent skill from VectorSpaceLab/AREX-Skill. Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring. Use when working with ForceField.createSystem, Modeller, bundled force-field XML files, residue template failures, solvation/hydrogenation/membranes, AMBER/CHARMM/GROMACS/Tinker inputs, or ffxml validation.

Its SKILL.md is about 990 tokens, which your agent loads only when the skill is triggered. The skill folder holds 7 other files, including scripts and reference files (for example `references/forcefield-api-and-data.md`, `references/forcefield-xml-authoring.md` and `references/model-building-recipes.md`).

The repository describes itself as: A Skill Library for Automated Machine Learning. The licence is MIT.

When your agent uses it

  • Working with ForceField.createSystem
  • Bundled force-field XML files
  • Residue template failures
  • Solvation/hydrogenation/membranes

Example prompts

  • “/force-fields-modeling”

Requirements

  • Python 3

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

  1. Identify whether the inputs are coordinates plus topology needing a ForceField, or already-parameterized files such as AMBER prmtop…
  2. Choose force-field XML files as a compatible set: main biopolymer file plus the matching water/ion or implicit-solvent file when needed.
  3. Use Modeller before createSystem() when the topology lacks hydrogens, solvent, membranes, or force-field-required extra particles.
  4. Run forcefield.getUnmatchedResidues(topology) or forcefield.getMatchingTemplates(topology) before debugging a full simulation when…
  5. Build the System with createSystem() using nonbonded settings that match the topology: periodic boxes generally pair with PME/cutoffs…
  6. Keep production dynamics, integrator choice, reporter setup, and platform precision decisions in sibling sub-skills unless they directly…

What it can do on your machine

Read from SKILL.md and the folder at commit ac3fe1a. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 1 file in scripts/ (Python), which the agent can run.

    Shell commands in SKILL.md call:

    • python

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Force Fields Modeling loads about 988 tokens when it runs, and up to ~11k if it reads all its reference files. Until then it costs about 90 tokens; SKILL.md has 388 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~90
When it runs · the whole SKILL.md, loaded when a task matches
~988
With references · SKILL.md plus every file in references/, read only if the agent opens them
~11k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from VectorSpaceLab/AREX-Skill at commit ac3fe1a, republished under its MIT licence (© VectorSpaceLab). 388 words, ~988 tokens.

Download SKILL.mdSave it as .claude/skills/force-fields-modeling/SKILL.md (or your agent's skills folder). This skill also uses 5 other files; get the full folder from GitHub.
name
force-fields-modeling
description
Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring. Use when working with ForceField.createSystem, Modeller, bundled force-field XML files, residue template failures, solvation/hydrogenation/membranes, AMBER/CHARMM/GROMACS/Tinker inputs, or ffxml validation.
disable-model-invocation
true
metadata.disco-role
operating
license
MIT, GPL, LGPL

Force Fields and Modeling

Use this sub-skill when a task is about preparing a molecular model or parameterizing it before a simulation in OpenMM.

Route Here For

  • Selecting bundled OpenMM ForceField XML files, compatible water/ion files, implicit solvent files, or polarizable force fields.
  • Calling ForceField.createSystem() with correct nonbondedMethod, cutoff, constraints, rigidWater, hydrogenMass, residue template, and external-bond options.
  • Editing structures with Modeller: add missing hydrogens, solvent, ions, membranes, extra particles, or remove incompatible water.
  • Diagnosing No template found for residue and related residue-template, terminal variant, water-model, bond, or extra-particle mismatches.
  • Loading parameterized inputs from AMBER, CHARMM, GROMACS, or Tinker instead of using ForceField XML directly.
  • Authoring or validating practical OpenMM force-field XML (ffxml) files and residue template generators.

Start With These References

  • references/forcefield-api-and-data.md for ForceField, bundled XML families, createSystem() options, and AMBER/CHARMM/GROMACS/Tinker input routes.
  • references/model-building-recipes.md for Modeller workflows: hydrogens, solvent, ions, water conversion, membranes, and extra particles.
  • references/forcefield-xml-authoring.md for ffxml structure, residue templates, patches, standard force tags, custom force wiring, and template generators.
  • references/troubleshooting.md for template mismatch diagnosis, water/ion compatibility, periodic-box and include-path problems.

Practical Workflow

  1. Identify whether the inputs are coordinates plus topology needing a ForceField, or already-parameterized files such as AMBER prmtop, CHARMM psf, GROMACS top, or Tinker xyz/key/prm.
  2. Choose force-field XML files as a compatible set: main biopolymer file plus the matching water/ion or implicit-solvent file when needed.
  3. Use Modeller before createSystem() when the topology lacks hydrogens, solvent, membranes, or force-field-required extra particles.
  4. Run forcefield.getUnmatchedResidues(topology) or forcefield.getMatchingTemplates(topology) before debugging a full simulation when template matching is uncertain.
  5. Build the System with createSystem() using nonbonded settings that match the topology: periodic boxes generally pair with PME/cutoffs; implicit solvent supports only non-periodic or limited cutoff choices.
  6. Keep production dynamics, integrator choice, reporter setup, and platform precision decisions in sibling sub-skills unless they directly affect model parameterization.
Show full SKILL.md (86 more words)Show less

Bundled Script

Use scripts/forcefield_modeling_check.py as a lightweight smoke check for an OpenMM installation and a minimal force-field/model-building path. It builds a tiny in-memory water topology, verifies template matching, creates a System, and prints a JSON summary without requiring source checkout files.

bash
python scripts/forcefield_modeling_check.py

Boundaries

  • For running or restarting complete simulations, use simulation-workflows.
  • For custom mathematical force expressions or custom integrator algorithms beyond ffxml wiring, use custom-forces-integrators.
  • For CUDA/OpenCL/HIP/CPU platform selection, precision, and performance tuning, use platforms-performance.
  • For modifying OpenMM internals, plugins, C++ extension development, or tests, use development-extensions.

© VectorSpaceLab, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (scripts, references) in skills/repositories/repo-skills/openmm/sub-skills/force-fields-modeling of VectorSpaceLab/AREX-Skill.

  • SKILL.md
  • references/forcefield-api-and-data.md
  • references/forcefield-xml-authoring.md
  • references/model-building-recipes.md
  • references/troubleshooting.md
  • scripts/forcefield_modeling_check.py

Open the folder on GitHubat commit ac3fe1a

Compare with similar skills

Force Fields Modeling next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Force Fields Modeling compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Force Fields Modeling this skillVectorSpaceLab/AREX-Skill328—~988Automated safety check: PassMIT
Model Bank Metadatalobehub/lobehub83k—~2kAutomated safety check: PassCustom licence
Choosing Openmed Modelsmaziyarpanahi/openmed5.5k—~1.9kAutomated safety check: PassApache-2.0
OmniRoute Model Catalogdiegosouzapw/OmniRoute74k1 repos~589Automated safety check: PassMIT
Harness Threat Modelruvnet/ruflo74k—~363Automated safety check: NotesMIT
OmniRoute Model Catalog CLIdiegosouzapw/OmniRoute74k—~554Automated safety check: PassMIT

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Questions about Force Fields Modeling

What does Force Fields Modeling do?

Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring. Force Fields Modeling is an agent skill from VectorSpaceLab/AREX-Skill. Choose and troubleshoot OpenMM force fields, model-building workflows, parameterized input formats, and ForceField XML authoring.

When should I use Force Fields Modeling?

Force Fields Modeling fits situations like: working with ForceField.createSystem; bundled force-field XML files; residue template failures; solvation/hydrogenation/membranes.

How do I install Force Fields Modeling in Claude Code?

Run `npx skills add VectorSpaceLab/AREX-Skill --skill force-fields-modeling -a claude-code`. Or copy the skill folder (skills/repositories/repo-skills/openmm/sub-skills/force-fields-modeling in VectorSpaceLab/AREX-Skill) into .claude/skills/force-fields-modeling in your project. Claude Code loads it when a task matches its description.

How do I install Force Fields Modeling in Codex?

Run `npx skills add VectorSpaceLab/AREX-Skill --skill force-fields-modeling -a codex`. Or copy the skill folder (skills/repositories/repo-skills/openmm/sub-skills/force-fields-modeling in VectorSpaceLab/AREX-Skill) into .agents/skills/force-fields-modeling in your project. Codex loads it when a task matches its description.

Can I use Force Fields Modeling in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add VectorSpaceLab/AREX-Skill --skill force-fields-modeling -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/force-fields-modeling, .gemini/skills/force-fields-modeling, .github/skills/force-fields-modeling and .opencode/skills/force-fields-modeling in your project.

What does Force Fields Modeling need to run?

Going by SKILL.md and its folder, Force Fields Modeling needs Python for the scripts in its folder and the command-line tools its instructions call (python). Our summary lists: Python 3.

Does Force Fields Modeling access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Force Fields Modeling safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Force Fields Modeling use?

Force Fields Modeling is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Force Fields Modeling use?

About 988 tokens (SKILL.md is roughly 4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 9.7k tokens, read only when the agent opens those files.

What are the alternatives to Force Fields Modeling?

Skills that share tags, products or a category with Force Fields Modeling: Model Bank Metadata (lobehub/lobehub, 83k stars), Choosing Openmed Models (maziyarpanahi/openmed, 5.5k stars), OmniRoute Model Catalog (diegosouzapw/OmniRoute, 74k stars) and Harness Threat Model (ruvnet/ruflo, 74k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Force Fields Modeling?

VectorSpaceLab (a GitHub organization) maintains it in VectorSpaceLab/AREX-Skill, which has 328 GitHub stars. The repository holds 159 skills in this directory. The repository was last updated on September 3, 2026.

Source: VectorSpaceLab/AREX-Skill on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.