Electron-impact state-to-state resolved cross sections and rate coefficients for the X(v) → A(v′) excitation in BeH molecules

Electron-impact cross sections are calculated for the v -> v' transitions occurring between the vibrational levels of the two X-2 Sigma(+) and A(2)Pi electronic states of the BeH molecule. The calculations are performed with the R-matrix method for a purely vertical electronic transition for energies from threshold to 15 eV, and by using a modified version of the Mott and Masssey approximation to extend the calculations to high energies and to vibrational excitations. Rate coefficients are also calculated for the same transitions. The calculated v-v' selective cross sections and rate coefficients both satisfy distinct scaling relationships, which can be represented in a simple analytic form.