---
title: "Charge density"
description: "Compute the real-space charge (and spin) density of the crystal. Returns Gaussian cube file(s) for visualization plus a compact JSON summary (spin channels, cube names). Also returns the deformation density (SCF density minus superposed neutral atoms), which shows where bonding moved charge: into bo"
url: "https://ouro.foundation/routes/mmoderwell/charge-density"
id: "2941faa7-deb2-48dd-9bc1-7efb7f28ebaf"
type: "route"
---

# Charge density

Route by @mmoderwell in #materials-science (all) · runs in the background · $0.0003/s (about $0.018/min), held up front and settled on actual runtime · typical run ~43 s

- Asset id: `2941faa7-deb2-48dd-9bc1-7efb7f28ebaf`
- Page: https://ouro.foundation/routes/mmoderwell/charge-density

Compute the real-space charge (and spin) density of the crystal. Returns Gaussian cube file(s) for visualization plus a compact JSON summary (spin channels, cube names). Also returns the deformation density (SCF density minus superposed neutral atoms), which shows where bonding moved charge: into bonds and lone pairs, away from cations. Useful for bonding, charge transfer, and magnetic density distributions.

## Inputs

- `file` (primary): the id of a file on Ouro (.cif)

## Body parameters

Send only the ones you mean to change; the defaults are tuned.

| Name | Type | Default | Description |
| --- | --- | --- | --- |
| scf_thr | number | 1e-7 | SCF convergence threshold on the charge-density residual (A… |
| kspacing | number | 0.3 | K-point spacing in 1/Å |
| hubbard_u | object \| null |  | Turn on DFT+U with an effective U in eV per element, e.g. {… |
| basis_size | "SZ" \| "DZP" \| "TZDP" | "DZP" | LCAO basis size: SZ (fastest), DZP (balanced), TZDP (most a… |
| mixing_beta | number \| null |  | Charge mixing step (0–1). Left unset, it is 0.2 for structu… |
| dft_functional | "PBE" \| "PBEsol" \| "LDA" \| "SCAN" | "PBE" | XC functional |
| initial_magmoms | number[] \| null |  | Signed starting moments in µB, one per atom in CIF site ord… |
| smearing_sigma_ev | number | 0.05 | Occupation smearing width in eV (converted to Rydberg for A… |
| reduce_to_primitive | boolean | false | Evaluate the primitive cell instead of the cell as uploaded… |

## Run it

From an agent connected to Ouro MCP (`https://mcp.ouro.foundation/mcp`):

```
execute_route(route_id="2941faa7-deb2-48dd-9bc1-7efb7f28ebaf", input_assets={"file": "<file id>"}, wait=false)
```

From Python (`pip install ouro-py`):

```python
from ouro import Ouro

ouro = Ouro()  # reads OURO_API_KEY
action = ouro.routes.execute("2941faa7-deb2-48dd-9bc1-7efb7f28ebaf", input_assets={"file": "<file id>"})
```

The call returns an action id at once. Read the result with `get_action(id=..., wait=true)` over MCP, or `ouro action wait <id>` from the CLI.