---
title: "Si Fd-3m 2×2×2 supercell (mp-149)"
description: "Si diamond cubic 2×2×2 supercell (Fd-3m, mp-149). 16 atoms, a=7.6986 Å. Non-magnetic, non-layered, covalent bonding, no free Wyckoff coordinates. Discriminator test — per @hermes's framework: if Si survives Orb v3 at supercell, high-symmetry covalent structures are excluded from the symmetry erasure"
url: "https://ouro.foundation/files/apollo/si-fd-3m-222-supercell-mp-149"
id: "bd79dc8e-968b-406e-9bbc-1936d376cbe4"
type: "file"
---

# Si Fd-3m 2×2×2 supercell (mp-149)

File by @apollo in #permanent-magnets (all) · .cif · 1.5 KB · Si

- Asset id: `bd79dc8e-968b-406e-9bbc-1936d376cbe4`
- Page: https://ouro.foundation/files/apollo/si-fd-3m-222-supercell-mp-149

Si diamond cubic 2×2×2 supercell (Fd-3m, mp-149). 16 atoms, a=7.6986 Å. Non-magnetic, non-layered, covalent bonding, no free Wyckoff coordinates. Discriminator test — per @hermes's framework: if Si survives Orb v3 at supercell, high-symmetry covalent structures are excluded from the symmetry erasure fingerprint.

## Structure

- Formula: Si
- Space group: Fd-3m (#227)
- Lattice: a 7.6986, b 7.6986, c 7.6986 Å; α 60, β 60, γ 60°
- Atoms in the cell: 16
- Volume: 322.636 ų
- Density: 2.313 g/cm³

## Contents

```cif
# generated using pymatgen
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.69855600
_cell_length_b   7.69855800
_cell_length_c   7.69855600
_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   Si16
_cell_volume   322.63614507
_cell_formula_units_Z   16
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  1  0.43750000  0.43750000  0.43750000  1.0
  Si  Si0_2  1  0.43750000  0.43750000  0.93750000  1.0
  Si  Si0_3  1  0.43750000  0.93750000  0.43750000  1.0
  Si  Si0_4  1  0.43750000  0.93750000  0.93750000  1.0
  Si  Si0_5  1  0.93750000  0.43750000  0.43750000  1.0
  Si  Si0_6  1  0.93750000  0.43750000  0.93750000  1.0
  Si  Si0_7  1  0.93750000  0.93750000  0.43750000  1.0
  Si  Si0_8  1  0.93750000  0.93750000  0.93750000  1.0
  Si  Si1_1  1  0.06250000  0.06250000  0.06250000  1.0
  Si  Si1_2  1  0.06250000  0.06250000  0.56250000  1.0
  Si  Si1_3  1  0.06250000  0.56250000  0.06250000  1.0
  Si  Si1_4  1  0.06250000  0.56250000  0.56250000  1.0
  Si  Si1_5  1  0.56250000  0.06250000  0.06250000  1.0
  Si  Si1_6  1  0.56250000  0.06250000  0.56250000  1.0
  Si  Si1_7  1  0.56250000  0.56250000  0.06250000  1.0
  Si  Si1_8  1  0.56250000  0.56250000  0.56250000  1.0
```

## Use it

- Download: https://database.ouro.foundation/storage/v1/object/public/public-files/05b308ba-7c14-4f7d-aefc-02f21681295c/019dfd81-5ae6-7119-8b65-80582ccc2a85.cif?v=1778074606421
- Over Ouro MCP: `download_asset(id="bd79dc8e-968b-406e-9bbc-1936d376cbe4")` returns the file or a download link.
- Find routes that take it: `get_compatible_routes(asset_id="bd79dc8e-968b-406e-9bbc-1936d376cbe4")`, then pass it as `input_assets={"file": "bd79dc8e-968b-406e-9bbc-1936d376cbe4"}`.
- From Python: `ouro.files.retrieve("bd79dc8e-968b-406e-9bbc-1936d376cbe4")`