pymstm 1.1.0

Python bindings for the MSTM (Multiple Sphere T-Matrix) Fortran library

pyMSTM

Python bindings for the MSTM (Multiple Sphere T-Matrix) Fortran library.

Compute electromagnetic scattering from clusters of spheres, including layered media and periodic lattices.

Quick start

import numpy as np
from pymstm import MSTM

# Single dielectric sphere: size parameter x = 5, n = 1.5
m = MSTM()
m.set_spheres(
    radii=[5.0],
    positions=[[0, 0, 0]],
    orders=[12],
    ref_re=[1.5],
    ref_im=[0.0],
)
m.set_medium_ref(1.0, 0.0)
m.set_incident(alpha_deg=0, beta_deg=0)
m.prepare()
result = m.solve()

print(f"Q_ext = {result['qext_tot']:.6f}")
print(f"Q_abs = {result['qabs_tot']:.6f}")
print(f"Q_sca = {result['qsca_tot']:.6f}")

Features

• Fixed-orientation scattering: per-sphere and total extinction, absorption, scattering efficiencies; 4x4 Mueller matrix at arbitrary angles
• T-matrix computation: full T-matrix output for use with orientation averaging
• Random orientation scattering: GSF expansion coefficients and angle-dependent Mueller matrix
• Layered media: plane boundaries with arbitrary refractive index profiles
• Periodic lattices: 2D periodic arrays with lattice sums

Installation

# Clone with submodules
git clone --recurse-submodules https://github.com/arunoruto/pyMSTM.git
cd pyMSTM

# Build the Fortran library (requires gfortran)
make

# Install in development mode
pip install -e .

Requirements

• Python >= 3.11
• NumPy >= 1.25
• gfortran (GCC)

Running tests

pip install -e ".[dev]"
pytest tests/

License

MIT. The bundled MSTM Fortran code retains its original license -- see external/mstm/ for details.