Theoretical study of the predissociation of the A2Π state of ZnF including quasi-diabatisation of the spin-orbit coupling

Abstract

The excited (2)Π electronic states of ZnF have been diabatized in order to simulate the (2)Π ← X(2)Σ(+) vibronic spectrum using a wavepacket propagation technique. The spin-orbit coupling functions within the (2)Π states and between the (2)Π and B(2)Σ(+) states have also been diabatized, as well as the dipole and transition moment functions. As the adiabatic electronic (2)Π states are strongly multi-configurational, the quasi-diabatisation scheme was based on the electronic wavefunction overlap along the reaction coordinate. The procedure leads to a repulsive (2)Π state reaching the first dissociation limit, Zn((1)S(g)) + F((2)P(u)), and a bound one associated with the second limit, Zn((3)P(u)) + F((2)P(u)). The adiabatic electronic potentials and coupling functions have been determined at the multi-reference-configuration-interaction level of theory. The vibrational energies and the spin-orbit splittings are in agreement with early experimental data. The wavepacket propagation approach, coupled with a Prony analysis, allowed also to analyze the resonances and the bound vibronic states of the (2)Π manifold. The (2)Π ← X(2)Σ(+) vibronic spectra have been determined for Ω = 1/2 and 3/2 originating to the v'' = 0 level of the X(2)Σ(+) state.