SEMICLASSICAL DYNAMICS IN UP TO 15 COUPLED VIBRATIONAL DEGREES OF FREEDOM

The threshold photodetachment spectra of the ArnI- (n=2-6) anions meas ured recently by Neumark and co-workers have been simulated semiclassi cally using the cellularized frozen Gaussian approximation of Walton a nd Manolopoulos. This is the first time that a semiclassical initial v alue method has been applied to a series of molecular problems with so many coupled degrees of freedom. It is found that the number of traje ctories required for convergence and the absolute error in the semicla ssical approximation both increase approximately linearly with the num ber of degrees of freedom. The simulated photodetachment spectra of th e smaller anions Ar2I-, Ar3I-, and Ar4I- are in satisfactory agreement with experiment and the simulated spectra of the larger anions show t hat the corresponding experimental spectra are dominated by hot bands. (C) 1997 American Institute of Physics.