PointGroup

A Python package for automatic molecular point group detection and ideal-gas thermochemistry built on top of the Atomic Simulation Environment (ASE).

It combines symmetry analysis with ASE’s thermochemistry tools to reduce manual setup and prevents errors in molecular thermochemistry workflows.

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Features

• Automatic point group detection from atomic geometry
• Symmetry number assignment
• Geometry classification (monoatomic / linear / nonlinear)
• Wrapper around ASE IdealGasThermo

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Requirements

• Python ≥ 3.10
• numpy
• scipy
• ase

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Installation

Clone the repository and install in editable mode:

git clone https://github.com/Lillejanur/pointgroup.git
cd pointgroup
pip install -e .

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Example usage point group detection

python

from ase.build import molecule
from pointgroup import PointGroupAnalyzer

atoms = molecule("H2O")

pga = PointGroupAnalyzer(atoms)

print(pga.pointgroup) # C2v
print(pga.symmetry_number) # 2
print(pga.geometry) # 'linear'

Example usage ideal gas thermo wrapper

python

from ase.build import molecule
from pointgroup import IdealGasThermoAuto

atoms = molecule("H2")

vib_energies = [0.5]  # eV; cm^-1 works with vib_unit='invcm' or vib_unit='cm^-1'

thermo = IdealGasThermoAuto(atoms, vib_energies, potentialenergy=0)

G = thermo.get_gibbs_energy(
    temperature=298.15,
    pressure=101325
)