Calculation of initial state-selected reaction probabilities by a minimal number of wavepackets

An approach for the calculation of a set of initial state-selected reaction probabilities is presented. The number of wavepackets which must be propagated is considerably smaller than the number of initial states in question. The approach is based on ideas developed previously for the direct calculation of reaction rates. Thus, the wavepackets employed can be interpreted as states of the activated complex. Taking the H + H2 reaction for J = 0 as an example, it is shown that all initial state-selected reaction probabilities up to a total energy of 0.75 eV can be extracted from a single wavepacket.