Electron Scattering with ASTRA: Helium and Molecular Hydrogen
Abstract
We present an implementation of electron-impact scattering in ASTRA, a close-coupling method based on transition density matrices previously applied to molecular photoionization. The scattering states are obtained with a pole-free Galerkin method with variational surface matching, which yields the scattering matrix and the channel-resolved amplitudes for elastic and electronically inelastic integral cross sections and molecular-frame differential cross sections. For helium, ASTRA reproduces elastic and inelastic cross sections over a broad energy range, resolves the He-(1s2s2 2Se) Feshbach resonance in both energy and angle, and captures the principal interference structures in the n=2 excitation angular distributions, in selected channels matching measured differential-cross-section ratios more closely than available benchmark calculations. For molecular hydrogen, target polarization and interchannel coupling are represented through additional close-coupling channels, without a fitted polarization potential or a separately constructed (N+1)-electron correlation space. Compared with the restricted-channel description, the expanded calculations substantially improve agreement with UKRmol+ for elastic and inelastic cross sections. We further report fully orientation-resolved three-dimensional molecular-frame angular distributions for state-resolved electron-impact excitation. These reveal pronounced stereodynamic effects that vanish upon orientational averaging: at 15 eV, excitation of the b3Σu+ state is more than eight times stronger for incident momentum parallel rather than perpendicular to the molecular axis. These results connect conventional scattering benchmarks with orientation-resolved collision dynamics and open the way to larger molecular targets.
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BibTeX
@misc{chattopadhyay2026electron,
title = {{Electron Scattering with ASTRA: Helium and Molecular Hydrogen}},
author = {Siddhartha Chattopadhyay and Thomas C. Allison and Luca Argenti},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41026},
eprint = {2610.41026},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41026},
}
RIS
TY - UNPB
TI - Electron Scattering with ASTRA: Helium and Molecular Hydrogen
AU - Siddhartha Chattopadhyay
AU - Thomas C. Allison
AU - Luca Argenti
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.41026
UR - https://arxiv.org/abs/2610.41026
AB - We present an implementation of electron-impact scattering in ASTRA, a close-coupling method based on transition density matrices previously applied to molecular photoionization. The scattering states are obtained with a pole-free Galerkin method with variational surface matching, which yields the scattering matrix and the channel-resolved amplitudes for elastic and electronically inelastic integral cross sections and molecular-frame differential cross sections. For helium, ASTRA reproduces elastic and inelastic cross sections over a broad energy range, resolves the He^-(1s2s^2 ^2S^e) Feshbach resonance in both energy and angle, and captures the principal interference structures in the n=2 excitation angular distributions, in selected channels matching measured differential-cross-section ratios more closely than available benchmark calculations. For molecular hydrogen, target polarization and interchannel coupling are represented through additional close-coupling channels, without a fitted polarization potential or a separately constructed (N+1)-electron correlation space. Compared with the restricted-channel description, the expanded calculations substantially improve agreement with UKRmol+ for elastic and inelastic cross sections. We further report fully orientation-resolved three-dimensional molecular-frame angular distributions for state-resolved electron-impact excitation. These reveal pronounced stereodynamic effects that vanish upon orientational averaging: at 15 eV, excitation of the b^3Σ_u^+ state is more than eight times stronger for incident momentum parallel rather than perpendicular to the molecular axis. These results connect conventional scattering benchmarks with orientation-resolved collision dynamics and open the way to larger molecular targets.
ER -