Trajectory calculations for atom-molecule reactions which define the potential energy in terms of a bond angle and (adjacent) bond distance coordinate system will show discontinuities due to the necessity of switching surfaces during a trajectory. We show how to remove these discontinuities for the F + H2 → HF + H surface, where a rotated Morse curvecubic spline potential function is used.
Chemical Physics Letters
Ottawa-Carleton Chemistry Institute

Wright, J.S, & Polowin, J. (Joel). (1986). Energy-conserving trajectories in bond-angle-bond-distance coordinate systems. Chemical Physics Letters, 131(3), 256–260. doi:10.1016/0009-2614(86)80556-5