TIME-DEPENDENT HARTREE APPROXIMATION APPLIED TO THE PHOTODISSOCIATION OF ICN

A time-dependent, quantum-mechanical calculation of wave packet dynamics in the Hartree approximation is applied to the nonadiabatic transition between the linear and bent excited state surfaces in ICN. The model of ICN photodissociation in the A continuum given by Goldfield et aL is used. Both the probability and the energy of the propagated Hartree wave packets are conserved. Starting with the ground wave packet on the linear excited state surface, there is a final transfer of about 24% probability to the bent excited state surface. The probability transfer is almost complete in 12 fs. The autocorrelation function for the absorption spectrum is significant for less than 5 fs and there is good agreement between the absorption spectrum calculated by the Fourier transform of the autocorrelation function and by the projection onto asymptotic states after 100 fs. Such an agreement suggests that the time-dependent Hartree approximation is a valid and good approximation for the problem. The absorption spectrum is resolved into I(2P3/2) and I*(2P1/2) components and these do not agree with the experimental results of Pitts and Baronavski, which supports previous conclusions that the Goldfield et al. ICN potentials are inadequate. Calculations of the CN rotational distribution as a function of the photolysis wavelength for both surfaces are also presented, and the results are interpreted using the wave packet picture. There is only qualitative agreement with the semiclassical results of Goldfield et al. and the recent time-independent, quantum coupled-channel calculations of Guo et al.