Electron-molecule scattering via R-matrix variational algorithms on a quantum computer
Abstract
Electron-molecule collisions play a central role in both natural processes and modern technological applications, particularly in plasma processing. Conventional computational strategies such as the R-matrix method have been widely adopted yet encounter significant scaling challenges in treating more complex systems. In this work we present a quantum computational approach that utilises the variational quantum eigensolver (VQE) and variations thereof to overcome these limitations. We explore a number of methods, including the use of number projection operators and simultaneous optimisation. We demonstrate the feasibility of our method on a model problem of electron scattering from the hydrogen molecule, with numerical results obtained using a noiseless classical simulator. We recover the full spectrum of the Hamiltonian within a chosen symmetry sector. Moreover, the optimal circuit parameters directly encode the R-matrix boundary amplitudes needed for subsequent scattering computations. To our knowledge, this is the first application of quantum algorithms to electron--molecule scattering, and specifically the first formulation of the R-matrix inner-region problem on a quantum computer.
Cite
@article{arxiv.2507.05514,
title = {Electron-molecule scattering via R-matrix variational algorithms on a quantum computer},
author = {Dario Picozzi and Jonathan Tennyson and Vincent Graves and Jimena D. Gorfinkiel},
journal= {arXiv preprint arXiv:2507.05514},
year = {2026}
}