Effective collision strengths for fine-structure forbidden transitions among the 2s^22p^3 levels of Neiv
Effective collision strengths for electron-impact excitation of the N-like ion Neiv are calculated in the close-coupling approximation using the multichannel R-matrix method. Specific attention is given to the 10 astrophysically important fine-structure forbidden transitions among the ^4S^o, ^2D^o and ^2P^o levels in the 2s^22p^3 ground-state configuration. The expansion of the total wavefunction incorporates the lowest 11 LS eigenstates of Neiv, consisting of eight n=2 terms with configurations 2s^22p^3, 2s2p^4 and 2p^5, together with three n=3 states of configuration 2s^22p^23s. We present in graphical form the effective collision strengths obtained by thermally averaging the collision strengths over a Maxwellian distribution of velocities, for all 10 fine-structure transitions, over the range of electron temperatures log T(K) = 3.6 to log T(K) = 6.1 (the range appropriate for astrophysical applications). Comparisons are made with the earlier, less sophisticated close-coupling calculation of Giles, and excellent agreement is found in the limited temperature region where a comparison is possible [log T(K) = 3.7 to log T(K) = 4.3]. At higher temperatures the present data are the only reliable results currently available.