Absorption spectra due to curve-crossing potentials: Time-dependent wavepacket calculations

The absorption spectrum due to a curve crossing between a bounded potential and an unbounded potential is investigated by using a time-dependent wavepacket method. The first model potentials are a harmonic potential and a negative harmonic potential. With an increasing coupling constant between these states, the population density in the bounded potential decays fast, and the absorption structure is diffused with an increasing asymmetry. However, this trend is not observed for very strong coupling, and the reasons for that are discussed. The second model potentials are a Morse potential and a repulsive potential. The absorption spectrum clearly shows the vibrational structure of both the bounded potential and the repulsive potential although a transition is allowed only to one of the excited states.