Classical-like trajectory simulations for accurate computation of quantum reactive scattering probabilities

A trajectory ensemble method is introduced that enables accurate computation of microcanonical quantum reactive scattering quantities, using a classical-like simulation scheme. Individual quantum trajectories are propagated independently, using a Newton-like ODE which treats quantum dynamical effects along the reaction coordinate exactly, and preserves the phase space volume element. The sampling of initial conditions resembles a classical microcanonical simulation, but modified so as to incorporate quantization in the perpendicular mode coordinates. The method is exact for one-dimensional or separable systems, and achieves ∼1% accuracy for the coupled multidimensional benchmark applications considered here, even in the deep tunneling regime.