> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/getting-started/jarvis.md).

# JARVIS-DFT in Duaer

In Duaer: NIST JARVIS-DFT computed materials with band gap, formation energy, energy above hull, space group, and 2D or 3D dimensionality. One successful search uses 1 credit.
## What you get

Duaer JARVIS-DFT searches the NIST JARVIS-DFT database, which includes many 2D materials. Rows carry key computed properties directly, so an agent can compare candidates without opening each page.

Pick Duaer Data → JARVIS-DFT in the node creator, or open the [data market](/getting-started/data-market.md). Related: [Materials Project](/getting-started/materials-project.md), [NOMAD](/getting-started/nomad.md), [Crystal structures (COD)](/getting-started/cod.md).

## When to use it

- Compare band gaps and stability of candidate semiconductors or 2D materials.
- Screen a composition for the most stable phase (lowest energy above hull).

## When not to use it

- Measured crystal data. Use [Crystal structures (COD)](/getting-started/cod.md).
- Exact experimental band gaps. DFT (OptB88vdW) tends to underestimate them; mbjBandGapEv is closer when present.

## Search on the canvas

1. Open the node creator and pick Duaer Data → JARVIS-DFT.
2. Fill Formula (such as MoS2). Optional: Elements.
3. Limit defaults to 10, max 20. Execute.

A search uses 1 credit only when it returns rows. No rows, wrong input, or an upstream failure uses 0.

## Call the API

- GET https://api.duaer.com/v1/data/jarvis?formula=MoS2
- Authorization: Bearer <Duaer key>

The call skill below matches Copy skill in the Duaer data market, with parameters, examples, and result fields.

## Call skill

Same text as Copy skill.

```
---
name: duaer-jarvis
description: >-
  Duaer JARVIS-DFT. NIST JARVIS-DFT computed materials with band gap, formation energy, energy above hull, space group, and 2D or 3D dimensionality.
  One successful search uses 1 Duaer credit.
---

# Duaer JARVIS-DFT

Duaer JARVIS-DFT searches the NIST JARVIS-DFT database, which includes many 2D materials. Rows carry key computed properties directly, so an agent can compare candidates without opening each page.

## When to use

- Compare band gaps and stability of candidate semiconductors or 2D materials.
- Screen a composition for the most stable phase (lowest energy above hull).

## When not to use

- Measured crystal data. Use https://skills.duaer.com/cod.md.
- Exact experimental band gaps. DFT (OptB88vdW) tends to underestimate them; mbjBandGapEv is closer when present.

## Call

`GET https://api.duaer.com/v1/data/jarvis?formula=MoS2`

Header: `Authorization: Bearer <Duaer key>`

Use an account key or a model API key.

Get a Duaer key: https://skills.duaer.com/keys.md

## Parameters

Provide `formula` or `elements`.

- `formula` — Formula such as MoS2. Matches the reduced formula.
- `elements` — Optional. Materials that contain all of these, such as Mo,S.
- `limit` — Optional. Rows to return, from 1 to 20. Default 10.

## Examples

- `GET https://api.duaer.com/v1/data/jarvis?formula=MoS2` — MoS2 phases, bulk and 2D.
- `GET https://api.duaer.com/v1/data/jarvis?elements=Ga,N` — gallium nitride and related entries.

## Result

The response is `{ "items": [...] }`. Each item has `source`, `title`, `url`, and `summary`, plus:

- `jarvisId` — JARVIS id, such as JVASP-664.
- `formula`, `elements` — composition.
- `spaceGroup`, `crystalSystem`, `dimensionality` — symmetry and 3D or 2D.
- `bandGapEv`, `mbjBandGapEv` — OptB88vdW and TBmBJ band gaps in eV.
- `formationEnergyEvPerAtom`, `energyAboveHullEv` — stability in eV per atom.
- `bulkModulusGpa`, `densityGcm3`, `sites` — other properties when computed.

Fields without a value are left out.

## Credits

A search that returns at least one row uses 1 credit.
An empty search, a search that finds nothing, or a failed search uses 0.
Wrong input returns 400 with a message and uses 0.
No remaining credits returns 402 and does not search.
A missing key returns 401.

## Related

- https://skills.duaer.com/materials-project.md — Duaer Materials Project
- https://skills.duaer.com/nomad.md — Duaer NOMAD
- https://skills.duaer.com/cod.md — Duaer Crystal structures (COD)

```
## Questions

### How many credits does a JARVIS-DFT search use in Duaer?

One credit when Duaer returns rows. A search with no rows or an error uses 0.

### Why are some Duaer JARVIS fields missing?

JARVIS did not compute every property for every material. Duaer leaves those fields out instead of showing placeholders.

## Related

- [Materials Project in Duaer](https://doc.duaer.com/getting-started/materials-project.md)
- [NOMAD in Duaer](https://doc.duaer.com/getting-started/nomad.md)
- [Crystal structures (COD) in Duaer](https://doc.duaer.com/getting-started/cod.md)