ROTIONS: A program for the calculation of rotational excitation cross sections in electron—molecular ion collisions Original Research Article

ROTIONS is a program for the calculation of cross sections for rotational excitation of linear molecular ions by electron impact. The cross sections can be obtained from input T-matrices and from the Coulomb—Born approximation for dipole (Δj = 1) and quadrupole (Δj = 2) transitions. The Coulomb—Born results can be used to augment the low partial—wave T-matrices to an effectively infinite number of partial waves.