FINDSYM: Crystal Structure Symmetry Detection

FINDSYM is a Python package for detecting and analyzing crystal structure symmetries. It provides tools to identify space groups, point groups, and Wyckoff positions in crystalline materials.

Features

• Space Group Detection: Automatically identifies the space group of crystal structures
• Point Group Analysis: Determines the point group symmetries
• Wyckoff Position Assignment: Assigns atoms to their corresponding Wyckoff positions
• Primitive Cell Finding: Converts structures to their primitive cells
• 3D Visualization: Interactive visualization of crystal structures (optional)
• Multiple File Formats: Supports CIF, POSCAR, XYZ, and other common structure formats

Installation

From PyPI (recommended)

bash pip install findsym

With visualization support

bash pip install findsym[visualization]

From source

bash git clone https://github.com/AniruthAnanth/findsympy.git cd findsym pip install -e .

Dependencies

• numpy >= 1.18.0
• ase >= 3.20.0 (Atomic Simulation Environment)
• spglib >= 1.16.0 (Space group library)
• matplotlib >= 3.3.0 (optional, for visualization)

Quick Start

Command Line Usage

```bash

Basic symmetry analysis

findsym structure.cif

With custom tolerance

findsym structure.cif --tolerance 1e-4

With 3D visualization

findsym structure.cif --visualize ```

Python API

```python from findsym import findsym

Analyze a crystal structure

result = findsym("SrTiO3.cif", tolerance=1e-3, visualize=True)

print(f"Space group number: {result['number']}") print(f"Point group: {result['point group']}") ```

Examples

Analyzing SrTiO3

```python import findsym

Load and analyze SrTiO3 structure

result = findsym.findsym("SrTiO3mp-4651primitive.cif")

Output will show:

- Space group information

- Standardized lattice parameters

- Wyckoff positions for each atom

- Symmetry operations

```

Batch Processing

```python import glob from findsym import findsym

Process multiple structures

for ciffile in glob.glob("*.cif"): print(f"Processing {ciffile}...") result = findsym(cif_file) print(f"Space group: {result['number']}") ```

Output Information

FINDSYM provides detailed symmetry information including:

• Space Group: International symbol and number
• Point Group: Point group symbol
• Lattice Parameters: Standardized unit cell
• Wyckoff Positions: Site symmetries for each atom
• Symmetry Operations: Complete set of symmetry transformations
• Equivalent Atoms: Grouping of symmetrically equivalent atoms

Supported File Formats

• CIF (Crystallographic Information File)
• POSCAR/CONTCAR (VASP)
• XYZ
• PDB
• And many others supported by ASE

Visualization

When using the --visualize flag or visualize=True parameter, FINDSYM creates an interactive 3D plot showing:

• Crystal structure with atoms colored by element
• Unit cell boundaries
• Proper atomic radii
• Structure information overlay

Advanced Usage

Custom Tolerance

```python

For high-precision structures

result = findsym("precise_structure.cif", tolerance=1e-5)

For experimental/noisy data

result = findsym("experimental_structure.cif", tolerance=1e-2) ```

Programmatic Access

```python from findsym.core import ( parseinput, findprimitivecell, identifypointgroup, matchtostandardspace_group )

Load structure

structure = parse_input("structure.cif")

Find primitive cell

primitive = findprimitivecell(structure)

Get space group

dataset = matchtostandardspacegroup(primitive, tolerance=1e-3) print(f"Space group: {dataset['international']}") ```

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Inspired by the original FINDSYM from BYU's Isotropy Software Suite
• Built on top of spglib for symmetry operations
• Uses ASE for structure handling
• Visualization powered by matplotlib