Comparison of second-order split operator and Chebyshev propagator in wave packet based state-to-state reactive scattering calculations.

A detailed comparison of the time-dependent wave packet method using the split operator propagator and recently introduced Chebyshev real wave packet approach for calculating reactive scattering processes is reported. As examples, the state-to-state differential cross sections of the H + H(')D(v(0) = 0,j(0) = 1) --> H(')D + H/H(')H + D reaction, the state-to-state reaction probabilities of the (16)O + (35)O(2) (v(0) = 0,j(0) = 0) --> (17)O + (16)O(18)O/(18)O + (16)O(17)O reaction, the H + O(2) --> O + HO reaction, and the F + HD --> HF + D reaction are calculated, using an efficient reactant-coordinate-based method on an L-shape grid which allows the extraction of the state-to-state information of the two product channels simultaneously. These four reactions have quite different dynamic characteristics and thus provide a comprehensive picture of the relative advantages of these two propagation methods for describing reactive scattering dynamics. The results indicate that the Chebyshev real wave packet method is typically more accurate, particularly for reactions dominated by long-lived resonances. However, the split operator approach is often more cost effective, making it a method of choice for fast reactions. In addition, our results demonstrate accuracy of the reactant-coordinate-based method for extracting state-to-state information.