MD–DIM simulations of the 3Πg(ion-pair)→3Πu(valence) red-shifted transitions of Cl2 in neon matrices

The mixed quantum–classical molecular dynamics (MD) calculations with the diatomics-in-molecules (DIM) interaction potentials have been performed to model the features of the emission spectral bands corresponding to the transition from the ion-pair 3Πg state to the valence 3Πu state of Cl2 in neon matrices. The matrix-perturbed potential curves of the trapped Cl2 molecule have been evaluated as the corresponding cuts through the Cl2@Nen multi-dimensional potential energy surfaces and the numerical calculations of the 3Πg(v′)→3Πu(v″) band positions and the Franck–Condon factors have been estimated along classical trajectories. The results of the simulations show a remarkable resemblance to earlier experimental findings; namely, the matrix environment causes red shifts in the (0, v″) band positions as well as noticeable changes in band intensities.