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A local linear least square (LLLS) method to fit multidimensional potential energy surface for quantum dynamics calculation is presented. The method uses only energy data points within a local area in multidimentional space. The potential is fit using a linear least square method with singular value decomposition. The method is tested in quantum dynamical calculation for three-dimensional H + H₂ reaction. The result indicates that the local linear least square fitting is accurate and computationally efficient.

The state-to-state and state-to-all reaction probabilities for He+CO(v,j)→He+CO(v',j') reaction at zero total angular momentum have been calculated by using a time-dependent quantum wave packet method. The time-dependent method used is based on Fourier Grid and Discrete Variable Representation (DVR) techniques. The time-dependent propagation of the wave packet is accomplished by an expansion in terms of modified complex chebyshev polynomials. The results show that the He+CO reaction is not reactive in the studied energy range.