Electron impact excitation of N-like ions from the ICFT R-matrix calculation

We carried out intermediate coupling frame transformation (ICFT) R-matrix calculations on N-like ions (11≤Z≤20), which included a total of 272 fine structure levels in both the configuration interaction (CI) and close-coupling (CC) collision expansions. Comparisons with previous theoretical values were made in terms of energy levels, radiative transition rates, and oscillator strengths. The effective collision strengths (ϒ) were estimated in the temperature range of 104-107 K. An excellent agreement with available computations was reached for dipole-allowed transitions, while differences in ϒ were found for non-dipole allowed and forbidden transitions. This discrepancy is mainly attributed to the difference in CC expansions. Our calculations provide a good supplement to the electron impact excitation data on N-like ions.