入门
在 Duaer 里查晶体结构（COD）
在 Duaer 里：按化学式、矿物名或关键词检索晶体学开放数据库（COD）的实验晶体结构：空间群、晶胞参数、年份、文献与 CIF 下载。一次成功查询用 1 额度。
能拿到什么
Duaer 数据市场里的「晶体结构（COD）」：按化学式、矿物名或关键词检索晶体学开放数据库（COD）的实验晶体结构：空间群、晶胞参数、年份、文献与 CIF 下载。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 → 晶体结构（COD），或打开 数据市场。相关：Materials Project、JARVIS-DFT、compounds。
适合做什么
- 查某矿物或化合物的实测晶胞参数与空间群。
- 获取 CIF 文件，导入结构查看器或模拟软件。
在画布里检索
- 打开节点创建器，选 Duaer 数据 → Crystal structures (COD)。
- 填 Formula（如 SiO2）或 Words（如 quartz）。
- 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/cod?formula=SiO2&limit=5
- 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-cod
description: >-
Duaer Crystal structures (COD). Experimental crystal structures from the Crystallography Open Database by formula, mineral, or words: space group, cell lengths, year, paper, and CIF download.
One successful search uses 1 Duaer credit.
---
# Duaer Crystal structures (COD)
Duaer Crystal structures searches the Crystallography Open Database, an open collection of about 500,000 measured structures of minerals, organics, and metal-organics.
## When to use
- Find measured unit cells and space groups of a mineral or compound.
- Get a CIF file to open in a structure viewer or simulation.
## When not to use
- Computed properties such as band gaps. Use https://skills.duaer.com/materials-project.md or https://skills.duaer.com/jarvis.md.
- Protein structures. Use https://skills.duaer.com/structures.md.
## Call
`GET https://api.duaer.com/v1/data/cod?formula=SiO2&limit=5`
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 `words`.
- `formula` — Formula of one formula unit, such as SiO2 or CaCO3.
- `words` — Optional. Mineral, compound, or author words, such as quartz.
- `limit` — Optional. Rows to return, from 1 to 20. Default 10.
## Examples
- `GET https://api.duaer.com/v1/data/cod?formula=SiO2&limit=5` — silica polymorphs.
- `GET https://api.duaer.com/v1/data/cod?words=perovskite` — entries that mention perovskite.
## Result
The response is `{ "items": [...] }`. Each item has `source`, `title`, `url`, and `summary`, plus:
- `codId`, `cifUrl` — COD id and CIF download link.
- `formula`, `mineral`, `chemicalName` — formula in Hill order and names.
- `spaceGroup`, `spaceGroupNumber` — Hermann–Mauguin symbol and number.
- `a`, `b`, `c`, `alpha`, `beta`, `gamma`, `volume` — cell lengths (Å), angles (°), and volume (ų).
- `year`, `journal`, `paperTitle`, `doi` — source publication.
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/jarvis.md — Duaer JARVIS-DFT
- https://skills.duaer.com/compounds.md
常见问题
Duaer 的晶体结构（COD）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 COD 接受什么样的化学式？
直接写，如 SiO2、CaCO3，不要括号；Duaer 会转换成 COD 用的 Hill 格式。
同组