Theoretical study of the predissociation of the A[sup 2] Pi state of ZnF including quasi-diabatisation of the spin-orbit coupling
The excited 2Π electronic states of ZnF have been diabatized in order to simulate the 2Π ← X2Σ+ vibronic spectrum using a wavepacket propagation technique. The spin-orbit coupling functions within the 2Π states and between the 2Π and B2Σ+ states have also been diabatized, as well as the dipole and transition moment functions. As the adiabatic electronic 2Π 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 2Π state reaching the first dissociation limit, Zn(1Sg) + F(2Pu), and a bound one associated with the second limit, Zn(3Pu) + F(2Pu). 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 2Π manifold. The 2Π ← X2Σ+ vibronic spectra have been determined for Ω = 1/2 and 3/2 originating to the v′′ = 0 level of the X2Σ+ state.