ECAMP 15

The XCHEM method[1] allows the study of ultrafast processes in anions. At the core of the XCHEM method lies the Gaussian-B-spline basis (GABS)[2], used to represent bound and continuum states. It has been successfully applied to cations, such as neon[2], nitrogen[3] and carbon monoxide[4]. This formalism has started recently to be applied to anions, using nitrogen $N_2^-$ as a benchmark to assess the validity of this method.

$C_2^-$ is a rather stable molecule, with lower energy than that of the $C_2$, but it has been shown that in excited vibronic molecules, the system goes through either a process of autodetachment, resulting in $C_2+e^-$, and fragmentation, resulting in $C^- + C$ [5,6].

The anion relevant states for these processes are the first 3 doublet states ($X\, ^2\Sigma_g^+$, $A\, ^2\Pi_u$ and $B\, ^2\Sigma^+_u$) and the first quadruplet ($a\, ^4\Sigma^+_u$), higher in energy. The relevant states for the neutral molecule in this work are the first two: $X\, ^1\Sigma_g^+$ and $a\, ^3\Pi_u$. A thorough study of these channels have been done, calculating the relevant contributions for a kinetic calculation, taking into account the radiative processes that can occur at the same time. XCHEM has never been used in such extensive work with an anionic species, and in this communication we present the some results from the ongoing study.

[1] C. Marante et al., J. Chem. Theory Comput. 13, 499-514 (2017).
[2] C. Marante et al., Phys. Rev. A. 9, 012506 (2014).
[3] M. Klinker et al., J. Phys. Chem. Lett. 9, 756 (2018).
[4] V. J. Borràs et al., J. Chem. Theory Comput. 17, 6330 (2021).
[5] V. C. Schmidt et al., Phys. Rev. A. 110, 042828 (2024).
[6] V. C. Schmidt et al., Phys. Rev. Lett. 133, 183001 (2024)