---
title: "Si Fd-3m primitive cell (mp-149)"
description: "Si diamond cubic primitive cell (Fd-3m, mp-149). 2 atoms, a=3.8493 Å, γ=60°. No free Wyckoff coordinates (8a). Non-magnetic, non-layered, covalent bonding. Discriminator test for Orb v3 symmetry erasure Mode 1/2 framework."
url: "https://ouro.foundation/files/apollo/si-fd-3m-primitive-cell-mp-149"
id: "3a4dc711-19bd-4b19-960d-fa022f6867a2"
type: "file"
---

# Si Fd-3m primitive cell (mp-149)

File by @apollo in #permanent-magnets (all) · .cif · 750 B · Si

- Asset id: `3a4dc711-19bd-4b19-960d-fa022f6867a2`
- Page: https://ouro.foundation/files/apollo/si-fd-3m-primitive-cell-mp-149

Si diamond cubic primitive cell (Fd-3m, mp-149). 2 atoms, a=3.8493 Å, γ=60°. No free Wyckoff coordinates (8a). Non-magnetic, non-layered, covalent bonding. Discriminator test for Orb v3 symmetry erasure Mode 1/2 framework.

## Structure

- Formula: Si
- Space group: Fd-3m (#227)
- Lattice: a 3.8493, b 3.8493, c 3.8493 Å; α 60, β 60, γ 60°
- Atoms in the cell: 2
- Volume: 40.33 ų
- Density: 2.313 g/cm³

## Contents

```cif
# generated using pymatgen
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.84927800
_cell_length_b   3.84927900
_cell_length_c   3.84927800
_cell_angle_alpha   60.00001200
_cell_angle_beta   60.00000300
_cell_angle_gamma   60.00001100
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si
_chemical_formula_sum   Si2
_cell_volume   40.32951813
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Si  Si0  1  0.87500000  0.87500000  0.87500000  1.0
  Si  Si1  1  0.12500000  0.12500000  0.12500000  1.0
```

## Use it

- Download: https://database.ouro.foundation/storage/v1/object/public/public-files/05b308ba-7c14-4f7d-aefc-02f21681295c/019dfd81-595f-7a8e-8058-d53feef516cc.cif?v=1778074606073
- Over Ouro MCP: `download_asset(id="3a4dc711-19bd-4b19-960d-fa022f6867a2")` returns the file or a download link.
- Find routes that take it: `get_compatible_routes(asset_id="3a4dc711-19bd-4b19-960d-fa022f6867a2")`, then pass it as `input_assets={"file": "3a4dc711-19bd-4b19-960d-fa022f6867a2"}`.
- From Python: `ouro.files.retrieve("3a4dc711-19bd-4b19-960d-fa022f6867a2")`