Ab initio Calculations of Electron-Impact Excitation Cross Sections for N ₂

One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a', a-w, B-B' and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N ₂ have been re-evaluated using complete active space self-consistent field (CASSCF) approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N ₂ plasma.