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Electron-impact excitation and ionization of molecular and liquid water using a pseudocontinuum method

Anthony Ferté1,*, Robin Santra1,2,3,†, and Ludger Inhester1,2,‡

  • *Contact author: anthony.ferte@desy.de
  • †Contact author: robin.santra@desy.de
  • ‡Contact author: ludger.inhester@desy.de
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Phys. Rev. Research 8, 033229 – Published 26 August, 2026

DOI: https://doi.org/10.1103/h7g3-r5s3

Abstract

We present an ab initio framework for computing inelastic electron scattering (IES) on isolated molecules and in condensed phases, focusing on liquid water as a prototypical target. Our method employs a pseudocontinuum treatment for electron-impact ionization. The scattered projectile is described by a plane wave, while the final states of the target, including the excited or ejected electron, are expanded in a square-integrable basis. This approach naturally describes the transition between the excitation and ionization regimes and enables molecular-hole-resolved IES cross sections to be extracted within a standard quantum-chemistry framework. For isolated water molecules, the computed IES cross sections agree with available experimental data. For liquid water, our calculations show that solvation has a small effect on the total IES cross section. We see, however, that the liquid environment leads to a substantial enhancement of electron-impact-induced ionization and a corresponding reduction of electron-impact-induced excitation. We discuss the total and hole-resolved single differential cross sections, offering a complete molecular picture of IES and paving the way toward a detailed simulation of radiation-damage formation in water.

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Phys. Rev. Research 8, 033229– Published 26 August, 2026
  • Received 15 December 2025
  • Accepted 5 August 2026
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