Inverse perturbation via singular value decomposition: Application to correction of potential surface for HCN

We report a new potential energy surface (PES) for HCN which is able to exactly reproduce experimentally measured eigenvalues for total angular momentum of J=0 and 1. The new PES is obtained by adding a correction Delta V to a previous PES of Bowman et al., and the correction Delta V is determined through a direct inversion technique based on first-order inverse perturbation via singular value decomposition as described in a previous publication. Since the PES of Bowman et al. is a good starting PES, the inversion calculation is relatively straightforward. A total of 51 and 20 experimental eigenvalues, respectively, for J=0 and J=K=1, including both the H-CN and H-NC configurations, are used in the inversion calculation. Absolutely accurate eigenvalues (maximum deviation of less than 0.01 cm(-1) from experimental values) on the new PES cm obtained. Since the potential correction Delta V is expressed in a basis set, the corrected new PES is an analytical function of the coordinates. The contours of the new PES and of the potential correction Delta V are plotted to show locations of the correction to the PES of Bowman et al. (C) 1997 American Institute of Physics

Time-dependent quantum wave packet study of the H+DCN -> HD+CN reaction

Time-dependent wave packet calculation for the reaction H+DCN-->HD+CN is carried out using the semirigid vibrating rotor target model [J. Z. H. Zhang, J. Chem. Phys. 111, 3929 (1999)] on the TSH3 potential energy surface [J. Chem. Phys. 105, 558 (1996)]. Reaction probabilities are calculated from various initial rovibrational states of the reagent. Reaction cross sections and rate constants are calculated and are compared with the previous results for the isotopic reaction H+HCN on the same potential energy surface. (C) 2002 American Institute of Physics

Stereodynamics studies of the Sr plus HF reaction using time-dependent quantum wave packet method

A time-dependent wave packet calculation is carried out for the Sr + HF reaction in three dimensions. The effects of the reagent initial excitation on the total reaction probabilities (final states summed) as a function of collision energy are studied for the upsilon = 0, 1 and j < 20 states of HF. It is found that the vibrational excitation can enhance effectively the Sr + HF reaction. A detailed study on steric effects for the reaction at zero total angular momentum is also performed. The calculated results show that the F side of the HF molecule is the most favorite side for reactive attacks and the reactivity strongly depends on the attack angle. (C) 2000 Published by Elsevier Science B.V