Effect of different choices of the Boltzmannized flux operator on thermal exchange and recombination reactions

The rate constants for recombination and exchange reactions are calculated using the flux correlation approach with a general form of the Boltzmannized flux operator, which can simultaneously describe the Kubo and traditional half-split forms. First, we consider an exactly solvable model, i.e., the free particle case, in terms of a new scaling function. Next, as a non-trivial case, we study the recombination and exchange reactions at very high pressure. Since the rate constant is calculated by Laplace transform of the flux correlation function, the result depends on how the Boltzmannized flux operator is chosen. We find that a choice of the flux operator affects the rate constant considerably. For the recombination reaction, the ratio of the rate constant in the half-split form to that in the Kubo form approaches zero in the high pressure limit.