S. Herve et al., Rotational and vibrational wave packet motion during the infrared multiphoton excitation of HF, J CHEM PHYS, 114(2), 2001, pp. 826-835
The time dependent quantum dynamics of molecular rotations and vibrations d
uring coherent infrared multiphoton excitation are investigated by calculat
ion of the time evolution of the wave packet in the rotational and vibratio
nal configuration space. Results are presented for the rovibrational motion
of HF using recent potential energy and dipole moment functions developed
elsewhere by ab initio calculations. Several initial conditions are studied
, from the single rovibrational ground state to a superposition of states w
ith different J quantum numbers corresponding to highly oriented molecules.
A careful examination of the rovibrational wave packet motion allows for a
simple interpretation of the rotational motion and the effects of differen
t initial conditions on the intramolecular kinetics. It is found that, depe
nding on the degree of orientation, the HF molecule undergoes very fast deo
rientation, faster than its "classical" rotational period, thus perturbing
the generation of a semiclassical vibrational motion during the excitation
process. (C) 2001 American Institute of Physics.