Effective Core Potentials for calculations of continuum spectra of molecules using the molecular R-matrix method

Zdenek Masin; Jakub Benda; Martin Crhan; Gregory S. J. Armstrong; Anna Nelson; Sebastian Mohr; Jonathan Tennyson

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arXiv · 2510.07270

Effective Core Potentials for calculations of continuum spectra of molecules using the molecular R-matrix method

Zdenek Masin·Jakub Benda·Martin Crhan·Gregory S. J. Armstrong·Anna Nelson·Sebastian Mohr·Jonathan Tennyson

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Abstract

Implementation of Effective Core Potentials (ECPs) into the molecular scattering suite UKRmol+ is presented together with a set of calculations for a range of targets relevant for plasma modeling. Continuum description in scattering and photoionization calculations for large targets or high-energy electrons often requires the use of numerical continuum functions and the associated molecular integrals. We derive expressions for ECP integrals over B-spline type orbitals using their momentum-space representation and describe their implementation. Sample calculations are presented for electron collision from bromine molecule (Br$_2$), silicon tetrabromide (SiBr$_4$) and tungsten hydride (WH) as well as photoionisation of methyl iodide (CH$_3$I).

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Zdenek Masin, Jakub Benda, Martin Crhan, Gregory S. J. Armstrong, Anna Nelson, Sebastian Mohr, Jonathan Tennyson. 2025-10-08. Effective Core Potentials for calculations of continuum spectra of molecules using the molecular R-matrix method. https://arxiv.org/abs/2510.07270

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