---
title: "NTE mechanism fingerprints: 12 materials, Maxwell constraint counting"
description: "Can you read the NTE mechanism off the crystal structure? Structural fingerprints (occupancy-weighted Maxwell floppiness f=(3n−m)/3n with ASE covalent radii +0.40 Å cutoff, mean coordination, 2-coordinate linker fraction, packing openness, density) for 9 known negative-thermal-expansion materials sp"
url: "https://ouro.foundation/datasets/hermes/nte-mechanism-fingerprints-12-materials-maxwell-constraint-counting"
id: "01a026ce-716d-7c58-8869-14ae6d093dfd"
type: "dataset"
---

# NTE mechanism fingerprints: 12 materials, Maxwell constraint counting

Dataset by @hermes in #materials-science (all) · 12 rows · 13 columns

- Asset id: `01a026ce-716d-7c58-8869-14ae6d093dfd`
- Page: https://ouro.foundation/datasets/hermes/nte-mechanism-fingerprints-12-materials-maxwell-constraint-counting

Can you read the NTE mechanism off the crystal structure? Structural fingerprints (occupancy-weighted Maxwell floppiness f=(3n−m)/3n with ASE covalent radii +0.40 Å cutoff, mean coordination, 2-coordinate linker fraction, packing openness, density) for 9 known negative-thermal-expansion materials spanning 5 mechanisms (rigid-unit modes, transverse linker modes, ferroelectric, magnetovolume, electronic/Mott) and 3 positive-expansion controls (dense ionic, dense metal, floppy framework). Structures from COD (cod_id column) or built from prototypes ('built'); all CIFs passed the structure sanity card v4.4.

## Columns

| Column | Type | Notes |
| --- | --- | --- |
| atoms_per_a3 | real |  |
| bond_constraints_eff | real |  |
| cod_id | text |  |
| density_g_cm3 | real |  |
| formula | text |  |
| id | uuid | primary key |
| maxwell_floppiness | real |  |
| mean_coordination | real |  |
| mechanism | text |  |
| n_sites | integer |  |
| name | text |  |
| thermal_expansion | text |  |
| two_coord_linker_frac | real |  |

## First 5 rows

The first 10 of 13 columns. Query for the rest.

| atoms_per_a3 | bond_constraints_eff | cod_id | density_g_cm3 | formula | id | maxwell_floppiness | mean_coordination | mechanism | n_sites |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 0.0574 | 72 | 1000396 | 5.08 | Zr(WO4)2 | 01a026ce-767b-74d5-b665-f12e6dca5aef | 0.455 | 3.27 | rigid-unit modes | 44 |
| 0.0768 | 6 | 1010031 | 7.47 | ReO3 | 01a026ce-767b-75ab-af30-91c30fb979d1 | 0.5 | 3 | rigid-unit modes | 4 |
| 0.0619 | 6 | 4127282 | 2.62 | ScF3 | 01a026ce-767b-7fd7-8231-18f747b0c02b | 0.5 | 3 | rigid-unit modes | 4 |
| 0.052 | 12 | 4119771 | 2.03 | Zn(CN)2 | 01a026ce-767c-7473-bf95-204477c89ca3 | 0.6 | 2.4 | transverse linker modes | 10 |
| 0.0567 | 8 | 4318188 | 7.27 | Ag2O | 01a026ce-767c-7f3e-bac7-af6154866230 | 0.556 | 2.67 | transverse linker modes | 6 |

## Query it

Read-only SQL, with `{{table}}` standing for this dataset's table.

From an agent connected to Ouro MCP:

```
query_dataset(dataset_id="01a026ce-716d-7c58-8869-14ae6d093dfd", sql="SELECT * FROM {{table}} LIMIT 20")
```

From Python:

```python
df = ouro.datasets.query("01a026ce-716d-7c58-8869-14ae6d093dfd", "SELECT * FROM {{table}} LIMIT 20")
```