Quantum reactive scattering in three dimensions: Using tangent-sphere coordinates to smoothly transform from hyperspherical to Jacobi regions

Hyperspherical coordinates are well suited for treating rearrangement proce sses in the strong interaction region, and several different hyperspherical coordinates have been used successfully for quantum reactive scattering by various research groups. However, it is well known that asymptotically the appropriate set of coordinates (for a three particle system) are the three sets of Jacobi coordinates. In this paper we show how one can smoothly con nect the hyperspherical coordinates in the rearrangement region to Jacobi c oordinates in the nonrearrangement region using tangent-sphere coordinates. This procedure reduces the computational time required to solve the quantu m Schrodinger equation and eliminates the need for numerical projection. To illustrate this method, we apply it to the F+H(2)reversible arrow HF+F rea ction, comparing reaction probabilities to those from previous benchmark ca lculations based on a conventional formulation. (C) 2000 American Institute of Physics. [S0021-9606(00)00622-X].