Total cross sections including elastic scattering, electronic excitati
on-ionisation and the dipole rotational excitation are calculated for
electron impact on HF, OH, NH, and CH molecules. The additivity rules
as well as single-centre expansion are employed for this purpose. A co
mparison was possible for the e-HF system only, Our results are expect
ed to be good at intermediate to high energies (> 50 eV).