Time-Dependent Wave Packet Split Operator Calculations on a Three-Dimensional Fourier Grid in Radau Coordinates Applied to the OClO Photoelectron Spectrum

Abstract

A transformed Hamiltonian for a triatomic molecule in Radau coordinates is employed for time-dependent wave packet calculations. The first photoelectron band of the OClO molecule is calculated by propagating the wave packet on a three-dimensional Fourier grid with the split operator method. To find the intial wave function, we first calculate the few lowest one-dimensional eigenfunctions along each Radau coordinate by the Fourier grid Hamiltonian method. The direct product of these eigenfunctions is then used as basis set for obtaining the initial ground state vibrational wave function, which in this way is expressed directly on the three-dimensional Fourier grid. Consistent with the results of a previous two-dimensional study, we find that the asymmetric stretch plays little role in the photoionization process. An improved equilibrium geometry for the potential energy surface function of the ground electronic state of OClO+ was found by iteratively comparing with the experimental photoelectron spectrum. Using the approach employed here, it is easy to treat a timed-dependent Hamiltonian.