Theoretical Study of Electron Scattering from Magnesium Sulfide

In this study, we investigate electron interactions with the magnesium sulfide (MgS) [1] molecule, the first metallic sulfide molecule detected in the interstellar medium (ISM). Its presence in the ISM is significant because metal-containing molecules in the gas phase are generally rare due to the refractory nature of metals. It is observed near the Galactic Centre, known as G+0.693-0.027 [1]. Its vertical ionisation threshold is reported at 7.64 eV [1], while the dipole moment is given as 7.07 Debye [1], which is quite high. A study of electron interactions with MgS is important, as it has applications in astrophysics, plasma physics, and interstellar chemistry. To understand how MgS interacts with electrons in astrochemistry modelling, scattering cross-sections are required. To determine various cross-sections, we employed the R-Matrix method [2] for low energies (below 15 eV) and used the spherical complex optical potential (SCOP) along with the complex scattering potential–ionisation contribution (CSP-ic) [3] for the energy range of 15–5000 eV. Low-energy electron interaction cross-sections are calculated using three models: static exchange (SE), static exchange and polarisation (SEP), and configuration interaction (CI). During the meeting, we will report the electron impact elastic, ionisation, total, excitation, and dissociative electron attachment cross-sections of MgS. The molecular structure is optimised for MgS, and different properties, such as dissociation energy, bond length, polarisability, and ionisation potential, are reported using the software Avogadro [4] and ORCA [5].

References

[1] Marta Rey-Montejo et al. Discovery of MgS and NaS in the Interstellar Medium and Tentative Detection of CaO. ApJ, 975, 174, 2024

[2] Tomer et al. Low-Energy Electron Scattering from Pyrrole and Its Isomers J Phys Chem A. 127, 12, 2023

[3] Yadav et al. Investigation of Electron Collisions with Organic Phosphates. J Phys Chem A. 129, 34, 2025

[4] M. D. Hanwell et al. Avogadro: an advanced semantic chemical editor, visualisation, and analysis platform. J. Cheminform, 4:22889332, 2012.

[5] F. Neese et al. The orca quantum chemistry program package. J. Chem. Phys., 152:224108, 2020.