The study of the core-level spectroscopy of the photodissociation process of BrCN molecule

Fewest-switches surfacing hopping (FSSH) simulations have been performed with the highlevel multi-reference electronic structure method to explore the coupled electronic and nuclear dynamics upon photoexcitation of cyanogen bromide (BrCN). The potential energy surfaces (PES) of BrCN are charted as functions of the Jacobi coordinates (R, θ). An in-depth examination of the FSSH trajectories reveals the temporal dynamics of the molecule and the population changes of the lowest twelve states during BrCN's photodissociation process, which presents a rich tapestry of dynamical information. Furthermore, the carbon K-edge X-ray absorption spectroscopy (XAS) are calculated with multi-reference inner-shell spectral simulations. The rotation of the CN fragment and the elongation of the C-Br bond are found to be the reason of the peak shifting in the XAS. Our findings offer a nuanced interpretation for inner-shell probe investigations of BrCN, setting the stage for a deeper understanding of photodissociation process of cyanogen halides molecules