The nuclear dynamics of the low-lying first four electronic states of the prototypical indenyl radical is
investigated based on first principles calculations to rationalize the experimental vibronic structure of the
radical. The study is performed following both time-dependent and time-independent quantumchemistry approaches using a model diabatic Hamiltonian. The construction of model Hamiltonians is
based on the fits of the adiabatic energies calculated from the electronic structure method. The
analyses of the static and dynamics results of the present study corroborate the experimental findings
regarding the shape of the spectrum, vibrational progressions and the lifetime of the excited state. Finally,
the present theoretical investigations suggest that the electronic non-adiabatic effect is extremely important
for a detailed study of the vibronic structure and the electronic relaxation mechanism of the low-lying
electronic states of the indenyl radical
