Simulation of ultrafast methyl iodide photodissociation followed by Coulomb explosion using multi-reference methods

Coulomb explosion imaging (CEI) is a powerful tool for monitoring molecular structure changes during a chemical reaction. We present a direct simulation of methyl iodide photodissociation followed by Coulomb explosion, mirroring a recent pump-probe experiment utilizing coincident ion momentum imaging [1]. Our simulation is conducted on pre-built potential energy surfaces using an efficient molecular dynamics program. These surfaces are constructed based on accurate electronic structures calculated using the multi-reference configuration interaction method. We provide a direct comparison with the experiment for the delay-dependent kinetic energy release (KER) signals. Additionally, we discuss the effectiveness and potential challenges of using CEI to map conical intersections in coordinate space.

[1] F. Ziaee et al., Phys. Chem. Chem. Phys. 25, 9999 (2023)