Hyperfine tensor and defect structure of T center

## About the dataset
This record provides all data to reproduce the hyperfine coupling analysis of a T center defect in silicon. The results are reported in "Long-lived entanglement of a spin-qubit register in silicon photonics". DOI: https://doi.org/10.48550/arXiv.2504.15467

## Files included
- **hyperfine_terms.npz**: NumPy archive containing three float arrays (`Fermi_contact`, `Dipolar`, `Hyperfine`) saved via `numpy.savez`.
- **POSCAR**: VASP format structure file specifying a 1002‑atom silicon supercell with a T center defect.

## Computational methods
- Electronic structure calculations were performed with VASP using the HSE06 screened hybrid functional.

## Usage & reuse
1. **Load hyperfine data in Python**
   ```python
   import numpy as np
   data = np.load('hyperfine_terms.npz')
   Fc  = data['Fermi_contact']
   Dip = data['Dipolar']
   Hf  = data['Hyperfine']

2. **Load defect structures using pymatgen**
   ```python
   from pymatgen.io.vasp import Poscar
   poscar = Poscar.from_file('POSCAR')
   structure = poscar.structure