> For the complete documentation index, see [llms.txt](https://doc.duaer.com/zh/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/zh/getting-started/omdb.md).

# 在 Duaer 里查Open Materials Database

在 Duaer 里：按化学式或元素检索 Open Materials Database 中的晶体结构，含晶胞化学式、原子位点数与周期性维度。一次成功查询用 1 额度。
## 能拿到什么

Duaer 数据市场里的「Open Materials Database」：按化学式或元素检索 Open Materials Database 中的晶体结构，含晶胞化学式、原子位点数与周期性维度。查到结果时用 1 额度，结果交给数字组织的下一个节点。

从节点创建器选 Duaer 数据 → Open Materials Database，或打开 [数据市场](/zh/getting-started/data-market.md)。相关：[Materials Cloud MC3D](/zh/getting-started/materials-cloud.md)、[晶体结构（COD）](/zh/getting-started/cod.md)。

## 适合做什么

- 查某组分在 openmaterialsdb.se 里的结构。
- 与其他 OPTIMADE 数据库交叉核对结构。

## 在画布里检索

1. 打开节点创建器，选 Duaer 数据 → Open Materials Database。
2. 填 Formula（如 CaMgO6Si2）或 Elements（如 Ca,Mg）。
3. Limit 默认 10，最大 20。执行。

查到结果才扣 1 额度；没有结果、输入有误或上游失败都不扣。

## 用 API 调用

- GET https://api.duaer.com/v1/data/omdb?formula=CaMgO6Si2
- Authorization: Bearer <Duaer key>

下方是与数据市场「复制技能」相同的英文技能，含参数、示例与返回字段。

## 调用技能（英文）

与数据市场「复制技能」一致。

```
---
name: duaer-omdb
description: >-
  Duaer Open Materials Database. Crystal structures in the Open Materials Database by formula or elements, with cell formula, sites, and periodicity.
  One successful search uses 1 Duaer credit.
---

# Duaer Open Materials Database

Duaer Open Materials Database searches the openmaterialsdb.se structure collection over OPTIMADE. It returns standard structure fields only.

## When to use

- Cross-check a structure against another open database.
- List structures that contain a set of elements.

## When not to use

- Band gaps or energies. Use https://skills.duaer.com/materials-project.md.
- 2D layers. Use https://skills.duaer.com/matpedia-2d.md.

## Call

`GET https://api.duaer.com/v1/data/omdb?formula=CaMgO6Si2`

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 CaMgO6Si2. Matches the reduced formula.
- `elements` — Optional. Materials that contain all of these, such as Ca,Mg.
- `limit` — Optional. Rows to return, from 1 to 20. Default 10.

## Examples

- `GET https://api.duaer.com/v1/data/omdb?formula=CaMgO6Si2` — diopside structures.
- `GET https://api.duaer.com/v1/data/omdb?elements=Ca,Mg&limit=5` — structures with calcium and magnesium.

## Result

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

- `structureId` — provider id.
- `formula`, `formulaCell`, `elements`, `sites` — reduced formula, cell formula, elements, and atoms in the cell.
- `periodicDimensions` — 3 for bulk crystals.

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-cloud.md — Duaer Materials Cloud MC3D
- https://skills.duaer.com/cod.md — Duaer Crystal structures (COD)

```
## Questions

### Duaer 的Open Materials Database检索扣多少额度？

查到结果时扣 1 额度；没有结果或出错不扣。

### Duaer Open Materials Database 返回哪些字段？

Duaer Open Materials Database 只返回标准 OPTIMADE 结构字段，如化学式、元素与晶格，没有能量等性质。

## 相关

- [在 Duaer 里查Materials Cloud MC3D](https://doc.duaer.com/zh/getting-started/materials-cloud.md)
- [在 Duaer 里查晶体结构（COD）](https://doc.duaer.com/zh/getting-started/cod.md)