# Mat DB Nist Janaf

> Query the NIST Chemistry WebBook (which includes JANAF thermochemical tables) for standard experimental thermochemistry properties.

- Skill: `learningmatter-mit/mat-db-nist-janaf` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add learningmatter-mit/mat-db-nist-janaf`
- Raw SKILL.md: https://api.skillmd.com/api/skills/learningmatter-mit/mat-db-nist-janaf/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: learningmatter-mit (https://skillmd.com/u/learningmatter-mit)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/learningmatter-mit/mat-db-nist-janaf

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# mat-db-nist-janaf

## Goal
To query experimental temperature-dependent thermodynamic properties and standard states (e.g. Standard Enthalpy of Formation $\Delta_f H^\circ_{298}$, Standard Entropy $S^\circ_{298}$, and $C_p$) from the NIST Chemistry WebBook and JANAF tables for benchmarking against DFT/MLIP calculations.

## Instructions

### Step 1. Query Thermochemistry Data

Use the `query_janaf.py` script to fetch thermodynamic data for a given chemical formula. The script automatically searches the WebBook for the closest matching standard element or compound and parses the HTML tables to extract the gas-phase or condensed-phase standard thermochemistry values.

```bash
# Env: base-agent
python .agents/skills/mat-db-nist-janaf/scripts/query_janaf.py <formula> <output_json>
```

Parameters:
- `formula`: The chemical formula to query (e.g., `CH4`, `CO2`, `H2O`).
- `output_json`: Path to the output JSON file where results will be stored.

## Constraints
- **Environments**: The scripts require the `base-agent` Conda environment.
- **Scraping Dependability**: This script utilizes HTML scraping (`beautifulsoup4`). If the NIST WebBook layout changes in the future, the table selectors may need to be updated.
- **Isotopes**: By default, the script skips explicitly isotopically-labelled variants (unless it's the only match) to return the standard natural-abundance compound.

## References
- Linstrom, P.J. and Mallard, W.G., Eds., *NIST Chemistry WebBook, NIST Standard Reference Database Number 69*, National Institute of Standards and Technology, Gaithersburg MD. [URL](https://webbook.nist.gov)
- Chase, M.W., Jr., *NIST-JANAF Thermochemical Tables, Fourth Edition*, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951.

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**Author:** Bowen Deng
**Contact:** [GitHub @learningmatter-mit](https://github.com/learningmatter-mit)