PointGroup

Overview

PointGroup is a Python package for analyzing point group and space group characters (irreducible representations) from tight-binding models (Wannier90/pythtb/respack format). It provides utilities for symmetry operation analysis, character calculation, and group symbol conversion, leveraging libraries such as spglib and seekpath. Some functionalities are under development.

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Main Features

• Tight-binding Model Wrapper
  • Wraps Wannier90/pythtb/RESPACK models, manages lattice/orbital/band/k-path information (TBModel class).
• Automatic Point/Space Group Detection
  • Uses spglib to detect international and Schonflies symbols and all symmetry operations (rotation/translation).
• Character Calculation
  • Computes the character (trace) for a given k-point, band, and symmetry operation (GetCharacter class).
• Symmetry Operation Classification
  • Classifies symmetry operations (rotation, mirror, inversion, etc.) and converts to Schonflies/international symbols.
• Visualization Support
  • Utilities for structure visualization (e.g., CIF export via ASE).
• Extended Character Tables
  • Built-in character tables for major point groups (pg_ch_extra).

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Directory Structure

pointgroup/
    __init__.py
    get_character.py      # Main class for character calculation
    tbmodel.py            # Tight-binding model wrapper
    sym_op.py             # Symmetry operation utilities
    schonflies.py         # Schonflies symbol conversion
    utils.py              # Logging/visualization utilities
    pglib/                # Point group helper modules
        judge_pg_sym_op.py
        output_manager.py
        pg_ch_extra.py    # Character tables
        transform.py
requirements.txt
README.md

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Example Usage

from pointgroup.tbmodel import TBModel
from pointgroup.get_character import GetCharacter

tb = TBModel(wannier_path="...", wannier_prefix="...")
tb.gen_pythtb()
gc = GetCharacter(tb)
char = gc.get_character(kidx=0, orb_idx=0, op_idx=0)
print("Character:", char)

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Dependencies

• numpy
• spglib
• seekpath
• pythtb
• RESPACK (optional)

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License

• GPL-3.0 License

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Notes

• This package is intended for research in quantum chemistry and solid-state physics.
• For details, see docstrings and test codes in each module.

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