Theoretical investigation of collisions between highly-charged N$^{5+}$ and N$^{6+}$ with He*

For X-rays and/or EUV photons observed in cometary and planetary atmospheres and from the heliosphere, a primary production mechanism is charge exchange (CX) due to the collision between highly charged solar wind ions and ambient neutral species. In the present work, CX due to N$^{6+}$($1s~^2S$)-He and N$^{5+}$($1s^2~^1S$)-He collisions has been investigated using the quantum-mechanical molecular-orbital close-coupling (QMOCC) and the atomic-orbital close-coupling (AOCC) methods. For the high charged N$^{5+}$ and N$^{6+}$, the electrons of He will be captured to very highly excited or doubly-excited states, which may lie in continua of various quasi-molecular channels. The multi-reference single- and double-excitation configuration interaction approach (MRDCI) has been applied and a large number of important configurations have been selected to compute the adiabatic potential and nonadiabatic couplings. Total and state-selective cross sections are calculated for energies between 10 meV/u and 10 keV/u and the autoionization process has been treated quasi-classically. The QMOCC results are compared to available experimental and theoretical data as well AOCC calculations.