# Low-Energy Electron and Positron Scattering by Lysine: Cross Sections and Theoretical Insights into Possible DEA Pathways

## TL;DR

This paper presents a theoretical study of how low-energy electrons and positrons interact with lysine molecules, revealing possible pathways for dissociative electron attachment.

## Contribution

The first theoretical investigation of electron and positron scattering by lysine, identifying possible DEA pathways.

## Key findings

- A π* resonance was identified at 3.95 eV (SE) and 2.73 eV (SEP) for electron scattering.
- A low-energy hydrogen loss pathway at 1.85 eV was found, consistent with prior DEA studies.
- Excited electronic states of lysine were calculated using TDDFT to explore Feshbach-type DEA pathways.

## Abstract

We report a theoretical investigation of low-energy electron
and
positron scattering by the lysine molecule. The calculations were
performed using the Schwinger multichannel method with different levels
of approximation for each projectile. The static-exchange (SE) and
static-exchange plus polarization (SEP) approximations were used for
electrons, while the static plus polarization (SP) approximation was
used for positrons. Our results for electron scattering show a π*
resonance centered at 3.95 eV for SE and 2.73 eV for SEP in the integral
cross section, as well as a large structure around 11.0 eV for SE
and 9.0 eV for SEP, which may be associated with overlapping σ*
resonances. For comparison purposes, since there are no theoretical
or experimental cross sections available in the literature, a semiempirical
relation was employed to estimate the value of the π* resonance.
We also compared the results obtained for electron and positron scattering,
showing similar behavior at very low energy due to the dipole interaction
and approximately the same order of magnitude from 2 to 6 eV. Differential
cross sections for both projectiles also exhibit the same dominant
wave pattern. To investigate the connection between the resonance
and the dissociative electron attachment (DEA), we calculated threshold
energies for hydrogen loss from different sites in the molecule, identifying
a low-energy channel (1.85 eV) consistent with previous DEA studies
on similar systems. Furthermore, excited electronic states of lysine
were obtained by using time-dependent density functional theory (TDDFT),
providing additional insight into possible Feshbach-type DEA pathways.
These results represent the first theoretical study of scattering
processes involving electrons and positrons with lysine and offer
a foundation for future experimental and computational investigations.