Siegert Scatter

Compute radial (partial-wave) Schrödinger scattering using the Siegert pseudostate (SPS) method. This library produces S-matrices, cross sections, Wigner time delays, and scattering lengths for user-defined potentials.

This library is an implementation of the Siegert pseudostate method for quantum scattering as described in:

Batishchev, P. A. & Tolstikhin, O. I. (2007). Siegert pseudostate formulation of scattering theory: Nonzero angular momenta in the one-channel case. Physical Review A, 75, 062704.
https://doi.org/10.1103/PhysRevA.75.062704

Installation

pip install siegert-scatter

Usage

See the K-He example below for a complete real-world use case.

Command-Line Interface

The package provides a CLI for computing scattering from tabular potential files.

Basic Usage

siegert-scatter --help
siegert-scatter scatter --help

siegert-scatter scatter potential.dat

siegert-scatter scatter potential.dat -N 100 -a 15 -l 10 --e-max 5.0 -v

Input Format

The potential file should contain two columns: r (Bohr) and V (Hartree). Lines starting with # are treated as comments.

# r(Bohr)  V(Hartree)
0.5        -10.0
1.0        -5.0
2.0        -1.0

Output Files

The CLI produces two output files:

• {prefix}.npz: NumPy archive with S-matrix, cross sections, time delays, etc.
• {prefix}.json: Summary metadata with parameters, version, and timestamp

Example: K-He Spin-Exchange Scattering

For a complete real-world example, see scripts/KHe-example/run_everything.py, which computes spin-exchange cross-sections for potassium–helium (K-He) collisions.

Note: The K-He example is a specialized workflow that is not part of the packaged CLI. It requires additional dependencies and input data. See the example README for details.

This example demonstrates the library's capabilities in the context of the following work:

Tsinovoy, A., Katz, O., Landau, A. & Moiseyev, N. (2022). Enhanced Coupling of Electron and Nuclear Spins by Quantum Tunneling Resonances. Physical Review Letters, 128, 013401.
https://doi.org/10.1103/PhysRevLett.128.013401

How to cite

If you use this software in your research, please cite it.

See the CITATION.cff file for citation metadata compatible with GitHub's citation feature.

License

MIT License. See LICENSE for details.