mat-equation-of-state

mat-equation-of-state is a skill for Claude Code, Codex from learningmatter-mit/AtomisticSkills. It costs 21 tokens per session (1,184 once invoked), scanned A, original, MIT.

A workflow for measuring how a crystal's energy changes as its volume is expanded or compressed. Fitting this relationship gives properties such as equilibrium volume and bulk modulus, which describes resistance to compression.

In plain words
What is it for?
Use it to apply volume changes to a relaxed crystal, calculate the energy at each volume, and fit an equation of state using a machine-learning atomic model.
Why use it?
It provides a structured way to extract basic mechanical and equilibrium properties from energy calculations instead of inspecting raw energy values manually.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it to apply volume changes to a relaxed crystal, calculate the energy at each volume, and fit an equation of state using a machine-learning atomic model.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/learningmatter-mit/atomisticskills/mat-equation-of-state
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add learningmatter-mit/AtomisticSkills --skill mat-equation-of-state
Clone the repo
git clone --depth 1 https://github.com/learningmatter-mit/AtomisticSkills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mat-equation-of-state

README.md
[![agentmods](https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/mat-equation-of-state/github.svg)](https://agentmods.dev/skills/learningmatter-mit/atomisticskills/mat-equation-of-state)
Your own site
<a href="https://agentmods.dev/skills/learningmatter-mit/atomisticskills/mat-equation-of-state"><img src="https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/mat-equation-of-state/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/learningmatter-mit/atomisticskills/mat-equation-of-state"><img src="https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/mat-equation-of-state.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,184 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00021 $0.01184
Opus 5 $0.00010 $0.00592
Sonnet 5 $0.00004 $0.00237
Haiku 4.5 $0.00002 $0.00118

Measured 6d ago against content hash 247d486a3879, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

mat-equation-of-state scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/calculate_eos.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/mat-equation-of-state/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Equation of State Skill

This skill provides tools for calculating the equation of state (EOS) of crystalline materials using Machine Learning Interatomic Potentials (MLIPs). The EOS describes the relationship between volume, energy, and pressure, allowing extraction of bulk modulus and equilibrium volume.

Goal

Calculate the equation of state for a material by applying volumetric strains, computing the energy-volume relationship, and fitting to the Birch-Murnaghan equation to determine the bulk modulus ($B_0$) and equilibrium volume ($V_0$).

1. Prerequisites

  • The appropriate MLIP wrapper must be available (MACEWrapper, MatGLWrapper, or FAIRCHEMWrapper).
  • matcalc must be installed in the relevant conda environment.
  • A relaxed structure file (CIF, POSCAR, or other ASE-readable format).

2. Choosing a Foundation Potential

EOS calculations require accurate total energies across different volumes.

[!IMPORTANT]

  • Use OMAT or MatPES trained models: These models (e.g., MACE-OMAT-0-small, CHGNet-MatPES-PBE, TensorNet-MatPES-r2SCAN) provide more reliable energy predictions.
  • MPtrj models can be used: Unlike phonon calculations, EOS is less sensitive to force accuracy, but OMAT/MatPES models are still recommended for best results.

Refer to the foundation-potentials skill for more details.

3. Calculation Workflow

To calculate the equation of state, use the calculate_eos.py script:

# Env: mace-agent
python .agents/skills/mat-equation-of-state/scripts/calculate_eos.py \
    --structure path/to/relaxed_structure.cif \
    --model_type mace \
    --model_name MACE-OMAT-0-small \
    --n_points 11 \
    --max_abs_strain 0.1 \
    --relax_structure \
    --output_dir research/my_folder/eos

Key Parameters:

  • --n_points: Number of strain points (default: 11)
  • --max_abs_strain: Maximum linear strain applied (default: 0.1 = ±10%, i.e. volumes spanning (1±0.1)^3)
  • --relax_structure / --no-relax_structure (default on): fully relax the input cell (ions and cell vectors) before the strain scan, so the scan is centred on this model's own equilibrium volume rather than whatever volume the input file happens to have. It does not control the per-strain relaxation -- matcalc relaxes every strained point regardless.
  • --allow_shape_change / --no-allow_shape_change (default on, matcalc >= 0.5): at each strain point relax the cell shape at constant volume as well as the ions. This is the E(V) a Birch-Murnaghan fit assumes -- the minimum energy at fixed volume. Symmetry forbids shape relaxation in cubic cells, so it changes nothing there; for anisotropic cells, freezing the shape overestimates B0.
  • --fmax: Force convergence tolerance for relaxation (default: 0.1 eV/Å)

Read the full file on GitHub · 76 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 76 lines · 21 tokens per session scan A 247d486a3879

Subscribe to this mod's changes

mat-equation-of-state is a skill published in the GitHub repository learningmatter-mit/AtomisticSkills (162 stars, last pushed 6d ago), licensed MIT. It adds 21 tokens to every session and 1,184 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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